Tips to simplify designs
We are going to explore the concept of Design for Manufacturability and Assembly, or DFMA, and its critical role in enhancing product design and manufacturing efficiency. DFMA is a systematic approach that focuses on simplifying the design of a product to make it easier and more cost-effective to manufacture and assemble.
By integrating DFMA principles early in the design process, companies can reduce production costs, improve product quality, and shorten time-to-market. This methodology encourages collaboration between design and manufacturing teams, ensuring that potential manufacturing issues are addressed proactively.
As we delve into DFMA, we’ll uncover strategies and best practices that can lead to significant improvements in both product performance and manufacturing efficiency.
Question everything, assume nothing, believe only that which can be measured and validated. It’s a hard road we all must travel, but the right road to bring your ideas through to mass production.
DFMA or DFM is the ‘head’ of the engineering design process, balancing the ‘heart’ of knowledge, brilliance and inspiration. Product design without inspiration is generally terrible, product design without DFMA is liable to be miserable, and unlikely to make a return on investment.
The principles embodied in DFM can be quite varied, because of the diverse nature of products. DFM for a PCB looks very different from the same analysis for a stent or an oil-well drill bit. But the principles are simple enough, even if the execution needs considerable tailoring.
The seven key steps in DFMA implementation are:
- Minimize the Number of Components:
Reduces assembly and ordering costs, reduces work-in-process inventory, simplifies automation and manufacturing processes
- Design for Ease of Part-Fabrication:
Simplify part geometry: avoid unnecessary features to streamline manufacturing
- Tolerances:
Ensure parts are designed within process capability limits: find the balance between manufacturing ease and functional requirements
- Clarity:
Design components to allow only one correct assembly method: prevents assembly errors and increases efficiency
- Minimize the Use of Wet Processes and Flexible Components:
Be careful in exploiting wet-processes, seek automation of these where unavoidable: limit parts like rubber, gaskets, and cables, which are harder to handle and assemble: focus on rigid components for easier manipulation and assembly
- Design for Ease of Assembly:
Use snap-fits and single sided fasteners, avoid stacked fasteners and double sided fitting: design products with a base component to accurately and quickly locate other parts
- Eliminate or Reduce Required Adjustments:
Design products to minimize the need for post-assembly adjustments: reduce and exclude the likelihood of misalignment and out-of-adjustment conditions
Jerry S.
Mechanical Engineer
"The holy grail of good speed, quality, and price for custom parts"
Jiga is the best way to get the parts you need, when you need them.
The right time for a DFM process to start is NOW. If now is at the concept stage, all the better. The sooner that your product accommodates the optimizations that DFM imposes, the less the cost and time influence it’ll suffer.
DFM, at its best, will challenge the design and the designers’ foundational thinking, to look beyond simply solving the functional execution of parts, sub-assemblies and the product construction/assembly. It will drive the entire process from go-to-whoa towards excellence.
Perhaps the most important thing to keep in mind in your DFM journey is that this is not a stage in your design, it’s an underpinning mindset. You can’t ‘commission’ DFM services except as a final check/review. If you treat DFM as a stage or service, you will miss opportunities and make your product design process more disjointed and less smoothly progressive – and above all, harder and longer.
Effective DFM relies on someone – typically you, since you’re reading this – to integrate all of the knowledge required. You’re going to need to draw on:
- In design team knowledge/experience
- In house manufacturing history and support.
- Supply chain knowledge in component design/specification, product design feasibility, assembly processes and product evaluation and testing.
In many ways, this last should be your biggest knowledge base and best checksum on your development, because supplier relations are what will deliver.
An effective DFMA process needs the supply chain – both in-house and our-source – engaged throughout. Supplier relations and open communications are your best tool to deliver the outcome that meets the need.
Caleb Vainikka
Founder at Cove Design
Design for Manufacturing isn’t lipstick you apply at the end – it’s the foundation you build upon from the start. Pick up the phone, talk to manufacturers, and be humble enough to learn from them. Your CAD skills mean nothing if no one can make your part.
Example for review
As with most practical and learning exercises, it’s usually best to dive into some examples to illustrate the nature of the process. What we will do is a light review of a product design that can then be referred to throughout as examples to explain the good, the bad and the ugly.
The example we will analyze throughout this paper is a card reader and door entry code panel design that is a classic mix of PCB in a box, high cosmetic and planned high volume product. This encompasses many of the rules we are proposing/discussing here and it breaks a lot of them, allowing us to go through layers of design revisions that will show you a path to a great DFMA enabled product.
The product design as received is both part count heavy, complex in layering and intricate to assemble. This is a design that isn’t production/tooling ready for a variety of details. These details sit on a fault line between design functional review and design manufacturability review – but that’s pretty normal and a factor in the DFM process that explains why it’s not a standalone event but an integrated characteristic of effective design.
Here’s a few faults we will address:
- The keypads (3 separate parts addressing 2 separate PCBs) design lacks details around key motion, haptic feedback (the click of action) and contacts. It’s also not moldable and imposes impossible requirements on the top cover molding making that a hard to mold part. This mixes design issues, DFM issues and product functional issues but that’s fairly normal in solving the differential equation that is product design.
Before: 3 keypad moldings, no functional details
After: The revised keypad is one piece, with functional haptic snap, Carbon pads added and proposal for color and laser etch of symbols/numbers included. Only the combining of 3 into 1 parts is strictly pure DFM!
The cosmetic top cover will be very hard to mold where the inter-key ribs are so narrow. This will likely result in poor flow, difficulty filling AND a weak component that will fail in use. Revision to larger sections by better use of the keypad space alleviates this issue.
Compare the before (left) and after (right) DFM – the ribs between the keys were much too narrow to mold well, the minor alteration of key size allowed them to be double the width which will flow much more readily and reduces the risk of voids or bad weld lines.
- It uses three PCBs in the design, which will require interconnects that are costly and unreliable, plus extra fasteners.
This before (left) and after (right) shows the PBC setups (with keypads to help position the PCBs in your imagination.
The multiple boards would all need to be connected by cables/ribbons and likely connectors. These all build in cost and reduce reliability, in addition to the extra assembly complexity.
A single board solution moves all of those interconnects into the PCB structure, making them testable, reliable and essentially free.
- It uses more moldings than the design really calls for, separating what should be single parts into multiple.
This before (left) and after (right) shows the merging of the two piece housing into one part to reduce tooling, assembly effort and cost.
Many of the parts are essentially unmoldable and must be reworked to deliver practical manufacturing outcomes. The main housing is both made in two parts, which makes little sense, and both parts are not moldable to varying degrees.
- It has many and varied fasteners that lack all detail about their fitment, made worse by multiple PCBs
- The assembly is poorly layered, partly because of the multiple PCBs
Additionally there are design features that present a mix of user-functional and manufacturing cost issues that are not strictly basic DFM but stray into it.
- The device is latched in place with two key operated off the shelf devices. It’s not at all clear that it needs to be removed in normal operations, so this looks like a piece of lazy design because a tamper-proof way of attaching it was required. The DFM implications are two relatively costly lock devices, where a simpler and less costly solution would suffice – and where a better thought mechanism might negate the need for this locking and integrate it into the moldings.
Question: Does the product need to be taken off the wall plate regularly, maybe justifying the locks?
Answer: No!
- The card swipe slot is both hard to access and poorly executed. This is definitely less of a DFM issue, but the grey area transition between DFM and functional design review is where good design can become great design. Card slots are virtually universally down-slide. Also the card is unguided, so it can misplace (corner-in) and thereby misread and maybe jam.
While not strictly a DFM issue, the cross-fed card slot is hard to use and atypical, where the right hand side – downward card slot is commonplace and familiar.
Kyle Shropshire
Design Engineer, Founder at Drawing Navigator, LLC
The best way to catch DFM issues early in the design process is to get feedback from the manufacturing people. As soon as a rough sketch is done, or a concept modeled, let the people who actually have to build the parts weigh in on the idea.
This is a great way to get practical feedback like making sure there is enough room for tools, and hands, to get everything machined and assembled. I have seen an incredible speed increase on an entire product line.
Down from around 27 hours for each part to 4 hours by including tooling features. The 6 meter long machine frames now have fixturing holes in the bases that line everything up before welding. Those same holes are then used to align every frame during machining so they all end up within 0.05mm of each other.
DFM at the concept stage
Design for Manufacturability (DFM) at the concept stage is pivotal in ensuring that your product can be produced resource-efficiently, cost-effectively, and with high quality. Centering your design thinking in DFM principles from the get-go of product development allows you to identify and mitigate potential manufacturing issues while they are concepts/ideas, long before they impose costly problems in time and budget. An aggressively proactive approach demands consideration of manufacturing constraints, materials and process issues and supply chain capabilities from the outset. This inevitably influences decisions on design features, material selection, supply chain and production processes.
At the concept stage, DFM drives towards simplification of the product, particularly focussing on minimizing assembly complexity, reducing the part count, creating sub-assembly/module boundaries and ensuring ease of assembly. This typically results in lower manufacturing costs, improved product reliability, and smoother production setup.
Material selection is a key driver of DFM at the concept stage. Designers choose materials that are readily available, cost-effective, and compatible with the specification. But material choices immediately influence manufacturing process options, so an iterative loop of evaluations is seminal in establishing a productive and secure direction for the concept to be embodied in a design. This imposes a balancing of material properties – strength, weight, chemical resilience, thermal capacity etc., with optimization of costs and supply chain reliability. Early collaborative engagement with suppliers will render invaluable insights into material and process options and the restrictions/opportunities in more exotic selections.
DFM heavily emphasizes designing using tolerance levels that are non-challenging with the chosen manufacturing methods – or driving towards more precision process options where unavoidable. This ensures minimum cost and sufficient accuracy for fit/function/endurance. A deeply processed understanding of the capabilities and limitations of manufacturing processes enables designs that deliver to specification, without waste in over-precision.
Advanced consideration of the assembly processes during the concept stage is vital, to avoid embedding late stage difficulties without knowing they’re set into the design. Products must be designed for ease of assembly, reducing the labor that can explode the BOM costs. This variously involves designing parts that are easy to align, free of fasteners where possible by snap-fits, minimize assembly tools and design to make assembly fool proof.
DFM at the concept stage requires a collaborative approach, bringing together designers, manufacturing engineers, and suppliers to validate that the product meets the wider expectations of the team. A holistic approach will deliver significant cost savings, improved product quality, fewer delays at pre-and-early production and an efficient manufacturing process.
This is a graphic that illustrates:
1. The decreasing capacity of changes to influence a design towards good manufacturing outcomes (green line) as the design process proceeds. It gets INCREASINGLY harder to make revisions once you have a design and you’ve shared it and tooled it.
2. Despite your diminishing power towards revolutionary influence upon the design as it progresses, the cost of changes quickly becomes astronomical (red line).
The result of this needs a mindset that demands that the hard decisions are taken earlier and are more right! In particular, decisions that get embodied in tooling become very costly and time consuming, so get your part lines, wall sections, draft angles etc well supported BEFORE metal is cut!
William Burke
CEO at FiveFlute
I often see teams rush through the concept design stage because they are eager to start building, and its totally understandable!
I try to encourage engineers and really everyone on the development team to take all the time they need at the concept stage to fully evaluate different candidate designs.
A huge amount of a product’s final cost is locked in due to decisions made during concept development and this takes significant work to understand and optimize.
DFM isn’t something you just “tack on” to the end of a project.
It’s best to think of DFM as a lens you can interrogate the design through at every stage, not just when you’re ready to start cutting steel and making parts.
Understand how DFM influences supplier selection
Design for Manufacturability (DFM) is a main supporting element in the product development process that influences every aspect of supplier selection, to varied degrees. The who, the where, the how much, the how many, and the what process questions all drive choices that create design feedback(s) that must be processed in real time, for a successful outcome.
In-house or Outsource: Designing for the available skills
In-house production:
- When designing for in-house production, it’s crucial to align the product design with the existing capabilities, machinery, and expertise of your in-house-manufacture environment. This ensures that the product is optimized for higher capability and more experienced manufacturing environments/processes.
- When commercial or technical drivers make in-house less attractive, outsourcing can open up process and volume capabilities that in turn create solution opportunities that must be accommodated early in design. This does not rule out the use of in-house capabilities where they fit and are cost effective. It does, however, enable the evasion of CAPEX or training costs.
Outsourcing:
- When outsourcing, the design must integrate good use of the capabilities of the chosen supplier, in order to not miss product opportunities by narrowed thinking. This demands the designers understanding their expertise, equipment, and processes to ensure these are productively utilized in the development of great outcomes.
- Selection criteria should include the supplier’s experience with similar products, their technical capabilities, and their ability to scale production if needed. This ensures the supplier can deliver high-quality products within the required timelines.
Material supply chains weigh heavily in the DFMA process.
Material supply chains weigh heavily in the DFMA process.
- Consumer and industrial products need reliable and repeatable material sources.
- Medical and aerospace products need layers of assurances – certificates of conformity, ISO processes, bonded stores, client certified and regulatory authority controlled supply chains.
- Military products need even more – compliance with the mil-spec standards in force in the sector are costly and burdensome – but necessary.
Identifying, auditing and working with suppliers of custom parts can be hard work, but without a rigorous process in this, even a product for an uncertified market can go horribly wrong! Here’s an example that we have direct experience of helping sort out:
When this part was specified in beryllium-copper spring brass and evaluated in the prototypes, it underwent 10,000 cycles of test adjustment with no detectable change in performance.
When the headphone went to production, the supplier decided that making it out of muntz-metal (very low grade brass made from scrap) wouldn’t make any difference! And mass production, with a headband closed by ultrasonic welding, went ahead without any quality/performance checks!
So the first 5000 headphones clicked for about 30 adjustments before going soft. Poor material certification, poor quality control and a rushed entry to production carried a heavy price. And the material cost saving? $0.005 per earcup!
Assessing who you are dealing with can be really hard – but it is a central strut of the DFMA process – if you don’t understand the supplier of the “A” in DFMA then all your hard work can be brought to zero value, by an insignificant and cheap part.
The verification process can be long and hard and it has many fall-over points for the unwary:
- Poor comms is the project killer and you must militate against it. Suppliers that don’t communicate will eventually be suppliers that don’t supply.
- Cutting through the marketing, spin and yes, even lies is an imperative feature of establishing supply chains that supply. Don’t take anything at face value – audit, get references, run trials, give yourself the space to build security in your understanding of the suppliers abilities and gaps.
- Address low quality fast – many suppliers will not be as good as they think – help them to see, help them to develop, or move on when there’s too big a gap.
- Precision depends on skill, care and equipment. If any one is lacking, you’ll not like the outcomes – but when a shop has great equipment they look good – and that might just be a smoke screen. Evaluate.
- Poor and patronizing engagement can be a very bad sign. The supplier who behaves like they’re stooping to win your work and doesn’t appear to offer the unwavering and quick support you KNOW you need will never be good for your needs..
- Poor business practices, bad working conditions, poor stock control and job tracking all add up to future troubles. A great idea is to get ‘lost’ when you visit, take a look round for counterfeits, mess, dangers etc. Trust your nose – for example a bad molder will always smell of burned plastic. Go to the toilet and go walkabout.
When you find the right supplier, you’ll quickly know it. It’s like sun on your face and happy thoughts – knowing this is another thing that you don’t have to police, to deliver the “A” in DFMA.
Large scale or small scale production
In many cases, the constraints on a design must be derived from expected volumes. This requires a moderate tolerance for risk, as a product that is targeted at high volume must be designed for high volume, even if the outcome in market scale is not certain. The need to re-design and re-tool in response to success may be tolerable – and it more usually is ruled out.
Where volume certainty is clearer – such as the next product in a successful sequence, or a bespoke and specialist low volume product – it is easier to be right, at the start!
Large scale production:
- For larger scales of production, designs tend to focus on automation, repeatability, and efficiency. This often means designing for high-volume manufacturing techniques such as robotized injection molding: automated part inspection: component ‘handedness’ and orientation features: fall-together construction: or automated assembly. However, make certain you design for the methods that work at, and are accessible at your expected scale.
- Suppliers with the capacity to handle appropriate scale production runs, in suitable manufacturing capabilities, with experience at the right scale operations is the ideal. You should avoid being the capability fulcrum or scale driver for your suppliers. Also be sure they have robust quality control systems in place to maintain consistency.
Small scale production:
- For limited volume production, flexibility and customization may be more important design considerations. This could involve designing for more manual or lightly automated processes that can be more easily established and adjusted. Tolerating a high labor content on low volume/high value products is more feasible and unlikely to overwhelm the BOM cost.
- Small-scale and adaptable suppliers who offer flexibility, quick turnaround times, and the ability to offer craftsman skills and handle bespoke or low-volume orders are typically quite appropriate in such cases. This may actually extend the possibilities in design in some ways, as difficult-to-get-right and high-tolerance work can be accommodated more easily than in high volume.
Local or distant suppliers
Supply chain geography is a fraught question with few clearly right answers. However, if you want minimum cost and you cannot automate production, you will very likely gravitate towards a low labor cost supply chain. Political as well as financial principles can be at play, so this is likely to be a company policy decision rather than under the designers control – but knowing where you are going is a key component in getting there in good order.
Local Suppliers:
- When working with local suppliers, designs can focus less on shipping and logistics constraints and more on ease of assembly and manufacturing efficiency. The ease of site visits can allow early and aggressive design evaluation that will tend to improve manufacturability.
- Proximity allows for better collaboration and quicker responses to issues. Local suppliers with strong logistics and supply chain capabilities are advantageous. Local suppliers can often provide better response times, operating in the same timezone and with less sought-after international status.
Distant Suppliers:
- For distant suppliers, it’s essential to design products that minimize shipping costs and risks. Designing for shipping, so low-density products can flat-pack to reduce shipping volume can be a serious design constraint. The disjoint in assembly processes, so shipping volumes are reduced and final assembly can be local, brings design constraints that can be hard to balance.
- Select suppliers with robust shipping and logistics expertise, proximity to shipping hubs and the ability to provide reliable long-distance support. It’s also important to consider potential tariffs, import regulations, and longer lead times.
Material supply chains
Material supply chains can be simple, when the choices are commodity level and straightforward. But those options cannot deliver against exceptional requirements and harsh conditions of environment/use. Wise and well thought through choices at the start can mean a low disruption in the process, later.
Material availability:
- Material availability can significantly impact design decisions. When preferred materials are scarce or have long lead times, designers may need to opt for alternative materials that are more readily available. Designing for aAvailability sometimes affects designing for optimum. However, necessity can drive inventive solutions and reduce costs by eliminating the exotic.
- Sources should be chosen based on their ability to link to supply chains with consistent and reliable access to necessary materials. This demands early evaluation of their supply chain stability, relationships with material suppliers, and inventory management practices, which can result in feedback into the design process that should be handled early, for lower impact.
Optimal design vs. Material constraints:
- Balancing optimal design with material constraints always requires compromises in material properties – strength, corrosion/finishing requirements, weight, or cost. You must be flexible and creative in implementing solutions that meet performance requirements while accommodating material constraints.
- Suppliers with broader and more exotoc-tolerant material sourcing options and the ability to suggest alternative materials can be valuable partners in ensuring production continuity and cost-effectiveness. However, more limited option sources can often deliver lower costs, as they have reduced complexity and overheads.
Chris Barton
Co-Founder & CEO at Drafter
How to work best with suppliers
Once vetted, ensuring clear communication with suppliers will speed up the process and save cost. The best way to communicate design intent is with a 2D GD&T drawing made for each part and assembly.
These drawings should contain all necessary information to ensure that there is alignment between you and the supplier on what is needed for the parts to be successful and what is critical to the function of each component.
Streamlined communication for DFM success
DFM is essential to ensuring that parts are optimized for production, reducing errors, and speeding up the manufacturing process. Clear and direct communication between buyers and suppliers is crucial to this process. Misunderstandings or delays can lead to costly mistakes, design flaws, or production inefficiencies.
DFM support from the Jiga team
With Jiga, customers can communicate directly with their manufacturing partner, and when needed, the Jiga support team becomes an active part of the conversation. This ensures you receive assistance without blocking direct communication with your supplier.
Direct collaboration for DFM with 3D viewer annotations
For critical Design for Manufacturing (DFM) discussions, Jiga’s platform lets suppliers and buyers collaborate directly using the 3D viewer annotation feature. This tool allows both sides to validate designs, clarify details, and address potential issues in real-time, ensuring nothing gets lost in translation.
Alan B.
Mechanical Engineer
"Hands-Down the Best Platform and Partner for Fast, Quality Parts"
Jiga is the best way to get the parts you need, when you need them.
Understand how DFM impacts product cost and quality
DFM has heavy impacts on product cost and quality. The ramifications of early decisions can echo through to mass production, so making informed choices early, and validating them repeatedly will deliver better outcomes.
Optimizing design material waste:
- When designs are optimized for manufacturability, material usage is lower waste. This not only reduces the functional-outcomes cost of raw materials but also minimizes the costs and challenges associated with waste handling. Techniques such as nesting parts within processes hot runners in multi cavity tooling, and reducing finishing/trimming by optimizing manufacturing processes can impact material efficiency.
Simplified assembly processes:
- Simplification and easing of the assembly processes reduces the number of steps needed for a finished product. Reducing the number of components, using snap-fit designs, simplifying process tooling and building essentially self assembling products all offer impact in this. This not only speeds up production but also reduces the potential for assembly errors, both lowering the cost and improving product quality.
Below are side-by side exploded views of the door lock product, illustrating the gains in simplification of assembly:
1. Screws are replaced by heat stakes and snaps as far as possible.
2. 3 PCBs are replaced by one, with sufficient real estate for more complex versions of the product to fit in the same footprint with small revisions.
3. 3 keypad components are integrated into one molding.
4. Two upper housing parts become one – with improved moldability.
5. The locks used to retain the product have become snaps.
6. Overall moldability has gone from poor to good even as the part count has dropped.
7. Layering is greatly improved, with the main housing acting as receptacle into which all parts are assembled.
8. Unspecified fitment of the speaker cover is now a simple snap-in with line of draw tooling features.
9. The key action is fully supported from the lower molding, reducing likely failures.
10. The card slot has moved to the side, for easier operation
After an aggressive DFM revision process, the improved simplicity of the door code product is very clear.
Reduced labor costs:
- DFM often involves designing products that are designed to be assembled with minimal manual intervention and no adjustment. Incorporating automation-friendly aspects makes the product volume/success ready for little to no additional development cost. Where manual labor is required, deskilled and more reliable/simple processes will still create benefits in reduced labor cost.
Enhance product quality early in the design:
- The active consideration of manufacturability early in product design averts potential manufacturing issues long before they become hard barriers to be crossed in the factory. This leads to fewer defects, easier transition to production and higher-quality products with consistent quality, reduced variability and enhanced overall product reliability.
Streamlines manufacturing process, lower production costs:
- Streamlined manufacturing processes are more efficient and cost-effective. DFM helps eliminate steps or move them back into integrated multi-function components rather than assembly tasks. These steps then become systematized and tooled as precision component supply rather than care-and-attention tasks in assembly. This reduces complexity and variability at assembly to make production as straightforward as possible. This both speeds up the manufacturing process and reduces machine/process setup, maintenance, and downtime.
Delivers higher-quality products:
- Higher-quality products are a direct result of a well-implemented DFM strategy. By designing for manufacturability, you can facilitate products that are built correctly the first time, leading to greater customer satisfaction, fewer returns, and a stronger market reputation.
Identify Simplifications to Reduce Part Count
Simplifying a product and reducing the part count can deliver considerable cost savings, better manufacturing setup/productivity, and improved product reliability. In our door code example, part count has gone from 32 to 11 – and with complex interconnects between PCBs entirely removed.
This is best characterized by the PCB setup before and after:
Modular design and interchangeability:
- Design the product with a modular approach that facilitates sub-system QA and less uncertainty at final-assembly test.
- Reduces the number of unique parts and potentially allows modules to be used across various products or variants.
- Modularity simplifies inventory management and allows for simpler upgrades and repairs.
Components with multiple functions:
- Design parts that serve more than one purpose, such as a single piece that provides both structural support and housing for electronics: or an enclosure that integrates flexible regions for sealed actuation of tact switches: or mechanical release actuator that integrates button with force delivery and return spring.
- This approach reduces the overall number of parts, simplifies assembly, and can improve product reliability by interconnects that provide potential failure points.
Integrated sub-assemblies combining multiple parts into single components:
- Integrate multiple parts into a single, more complex part that can be manufactured as one piece. This pushes complexity upstream into high repeatability processes like molding, forging and machining.
- This approach reduces part count, assembly time and the potential for assembly errors.
- This is a major step in implementing Industry 4.0 adaptations in your products.
Standardization with off-the-shelf parts:
- Exploit standardized parts that are readily available and used across multiple products. These can be prior use/validation in-house designed parts or of the shelf components, similar benefits accrue.
- Reducing use of custom parts lowers costs and simplifies supply chain management.
- Off the shelf parts are usually cheaper because of larger volumes and have well-documented performance characteristics. In house designed parts reused shortcuts development and operational setup in similar ways.
Simplified fasteners:
- Use a minimized number of fastener types and sizes throughout the product.
- Design parts that can be assembled using fewer fasteners.
- Where multiple/varied fasteners must be used, aim for a common driver and torque settings across any module to simplify the assemblers tasks.
- Reduce the number of tools required for assembly to simplify the assembly process.
Layered assemblies:
- Design products to minimize the number of separate layers or components that need to be assembled.
- Combine multiple functions into single layers where possible.
- Simplifies assembly and reduces the part count.
Use of snap-fits in place of tool-executed fasteners:
- Design snap-fit connections instead of distinct fastener components.
- Snap-fits can be assembled quickly without tools, easing assembly process burdens.
- Well designed snap fits integrate disassembly capability for repairs or recycling.
Minimize adjustments post-assembly:
- Design parts to fit together precisely without the need for adjustments.
- Use manufacturing processes with appropriate tolerances to ensure parts fit correctly but are not expensive over-specified.
- Reduces assembly time and ensures product function.
Use processes for final shape and integrated functions:
- Use advanced manufacturing processes that produce parts closer to their final shape, reducing the need for additional machining or finishing.
- Integrate multiple functions into single parts to reduce the overall number of components.
- Examples include precision casting, additive manufacturing, progressive stamping, and multi-material injection molding and/or over-molding.
Six principles of implementing Poka-Yoke (Japanese for mistake-proof)
Poka-Yoke, a Japanese term meaning “mistake-proofing” or “error-proofing,” is a technique used in manufacturing to prevent errors by designing processes and products in such a way that mistakes are either impossible or immediately detectable. Implementing Poka-Yoke involves several key principles:
Prevention over detection:
- Design processes to exclude errors from occurring rather than allowing them and detecting them after the fact.
- Incorporate features that make it impossible to perform a task incorrectly. Examples are: designing connectors that can only fit in one orientation: keying parts so they are sexed and aligned with clarity and certainty.
Simplicity and accessibility:
- Keep error-proofing solutions simple and easy to implement, make them obvious with assembly indicators integrated into parts.
- Use straightforward methods that require minimal training or changes to existing processes. For example, using color-coding or shapes to guide assembly and make the process steps obvious with numbering for clarity and to tie-back to work instructions.
Immediate feedback:
- Provide intrinsic feedback to the assembly operator when an error occurs.
- Design systems that alert operators instantly if an error is made, allowing for quick correction. The ideal is parts that simply cannot be fitted in any but correct orientation/position.
Error detection and correction:
- Implement mechanisms to detect and correct errors as they occur. This can be alignment markers, or single orientation features, or wires too short to reach misplaced parts, or colors unmatched or a range of other features.
- Use visual inspection, or optical sensors, or imaging tools or other sensors to identify mistakes and halt the process, prompting immediate correction for re-start.
Source inspection:
- Inspect the process at the source rather than at the end. Making sure each stage is correct before implementing the next avoids value add on top of error.
- Integrate checks and controls at each stage of the process to flag errors immediately.
Fail-safe design:
- Design products and processes to fail safely, minimizing the impact of errors.
- Ensure that if a mistake is made, it does not cause harm or significant disruption. For example, design a machine to default to a safe mode, if a fault is detected, preventing damage or injury.
Implementing Poka-Yoke involves focusing on preventing errors through simple, accessible and operator-evident indicators that provide timely feedback and drive error correction. By inspecting processes at the source and designing fail-safes, Poka-Yoke enhances the reliability and safety of manufacturing operations and creates robust operation stages and systems for higher quality and efficiency in production.
Design for assembly (Mechanical and electronic products)
Electronics assembly DFM approaches and benefits: Designing for ease of assembly in electronics is essential to streamline manufacturing, reduce costs, and ensure high-quality products:
Minimize part count:
- Reducing the number of components simplifies assembly, reduces the chance of errors, lowers inventory costs, and shortens assembly time.
Combine multiple functions into single components. Use chip arrays for passives, logic gates, flip-flops etc.
Employ modular designs to reduce the number of unique parts.
Use custom silicone, FPGA etc to increase compactness and decrease connection counts.
Optimize PCB layout:
- An optimized PCB layout ensures efficient use of space, reduces signal interference, and simplifies assembly and testing.
Arrange components logically to minimize trace lengths and avoid crossings and the need for vias and additional PCB layers.
Group interacting components to simplify analysis for faults.
Consider the assembly sequence during layout to minimize difficulties in soldering.
Standardize components:
- Standardization reduces complexity, simplifies sourcing, and ensures compatibility across different products.
Use common, widely available components.
Limit the variety of components to those that are essential.
Select component formats that are compatible with automated assembly processes.
Facilitate soldering to suit the device tech (PTH, SMT, hybrid):
- Properly designed solder joints ensure reliable electrical connections and mechanical strength.
Design for uniform pad sizes and shapes to improve soldering repeatability.
Use thermal relief pads around heat sensitive components to aid in heat dissipation during soldering.
Ensure sufficient spacing between pads to prevent solder bridges.
Ensure Effective Thermal Management:
- Effective thermal management extends the lifespan of electronic components and maintains performance.
Incorporate heat sinks and thermal vias in the PCB design.
Use materials with good thermal conductivity.
Design airflow pathways for cooling.
Incorporate 100% Nodal Access Test Points:
- Access to all nodes ensures easier automated and manual testing, crucial for identifying defects early in the production process.
Place test points for all critical signals and power rails.
Ensure test points are accessible without obstructing other components.
Use standardized test point markers for easy identification.
Use Keyed Connectors to Prevent Misalignment:
- Keyed connectors ensure correct orientation during assembly, preventing misalignment and potential damage.
Design connectors with unique shapes or keys that only fit in one orientation.
Use color-coding or labels to assist in correct assembly.
Ensure connectors are robust and easy to engage/disengage.
Automate Assembly When Volume Allows:
- Automation increases efficiency, reduces labor costs, and minimizes human error.
Design PCBs and assemblies that are compatible with pick-and-place machines.
Use components and materials suitable for reflow or wave soldering.
Implement automated optical inspection (AOI) and testing.
Ensure Robustness:
- Robust designs lead to reliable and durable products, reducing returns and warranty costs.
Design for environmental tolerance, including temperature, humidity, and vibration.
Use components with proven reliability and long lifespans.
Incorporate design margins to account for variations in manufacturing and material properties.
Collectively applied, these techniques make easier production, more reliable soldering, higher first pass yield and easier fault tracing. In total, better design makes lower cost and more rugged PCBa outcomes.
Mechanical product assembly (including PCB in a box product).
DFM principles enhance manufacturing efficiency, reduce costs, and improve product quality. Mechanical assembly covers a broad spectrum from ship building to PCB in a box consumer products, from progressive die stamped and overmolded connector parts to site assembly of a wind farm. However, some simple rules guide effective design irrespective of scale:
Minimize part count by integration:
- Reduces assembly time and costs: simplifies inventory management: and enhances reliability by reducing the potential for part failure
- Function Integration. Design parts that can perform merged functions, such as a single molded piece that acts as both a structural support and a spring.
Multi-functional components. Use components that integrate several functionalities, such as combining brackets and mounting points into one part.
Reduce assembly steps. Create sub-assemblies that integrate multiple smaller parts into a single unit.
Use standard fasteners:
- Lowers procurement and inventory costs: simplifies assembly by reducing the variety of fasteners and required tools: enhances ease of maintenance and repair
Standardize sizes and types. Choose common fastener types and sizes that are widely available and can be used across multiple products.
Unified fastening methods. Use the same fastening methods (e.g., screws, bolts) throughout the product to minimize tool changes.
Industry standards. Adhere to industry standards for fasteners to ensure compatibility and availability.
Optimize part and product orientation:
- Simplifies assembly processes: reduces the need for repositioning parts during assembly: improves ergonomic conditions for workers.
Design to exploit gravity. Orient parts in a way that leverages gravity to assist in assembly, such as placing heavier components lower to provide stability.
Single orientation. Design parts to fit in only the correct orientation to obviate assembly errors.
Clear markings. Use visual cues or markings to indicate correct orientation.
Design for easy PCB placement/retention:
- Increases product reliability: reduces assembly labor.
Design for drop in. Make PCB mount points features integrated into the housing, with placement of PCBs onto posts.
Fastener free retention. Use the housing to clamp the PCB into place to avoid additional fixings
Manage cables for easy assembly. Build in cable management features in the housing to reduce complexity.
Facilitate easy handling:
- Reduces the risk of damage during assembly: increases assembly speed and efficiency: improves worker safety and ergonomics
Ergonomic design. Design parts with features that make them easy to grip and manipulate.
Weight considerations. Keep part weights manageable for manual handling or design them for easy use with lifting aids.
Handling features. Incorporate handles, grips, or indentations to facilitate handling.
Use self-locating features:
- Speeds up assembly by ensuring parts align correctly without manual adjustment: reduces the risk of assembly errors: improves product consistency and quality.
Alignment pins and holes. Include pins and corresponding holes that ensure parts fit together correctly.
Snap-fit designs. Use snap-fit features that guide parts into the correct position.
Tapered lead-in. Design parts with tapers to help guide them into place.
Design for efficient (Tool-free) connection:
- Simplifies and speeds up assembly: reduces the need for specialized tools: lowers labor costs
Snap-fits. Use snap-fit connectors that require no tools for assembly or disassembly.
Quick-release mechanisms. Incorporate quick-release latches or clips for easy connection and disconnection.
Interlocking features. Design parts that interlock securely without the need for additional fasteners.
Use modular design thinking:
- Enhances flexibility in manufacturing and assembly: simplifies maintenance and upgrades: allows for customization and scalability
Interchangeable modules. Design modules that can be easily swapped or replaced.
Standard interfaces. Use standardized interfaces to connect different modules.
Independent sub-assemblies. Create sub-assemblies that can be independently tested before being final-assembly integrated.
Allow for automation:
- Reduces labor costs and increases production speed: enhances consistency and precision in assembly: minimizes human error
Robotic compatibility. Design parts and assemblies that can be easily handled by robots.
Automated fastening. Use fasteners and assembly methods that are compatible with automated tools.
Clear access points. Ensure parts have clear and accessible points for robotic arms to grip and manipulate.
Consider accessibility:
- Simplifies maintenance and repairs: enhances user experience by making products easier to service: reduces downtime in manufacturing and usage
Maintenance access. Design products with easy access to components that require regular maintenance or replacement.
Tool-free access. Use tool-free designs where possible to simplify access.
Clear layout. Arrange components in a logical and accessible manner, minimizing the need to disassemble other parts to reach them.
The greatest impact in terms of both assembly errors and labor cost in box-build lies in DFM optimization of assemblies so they pass the bucket test:
- The bucket test is a thought experiment. Go into stores with a picking list and a bucket. Pick the arts, place them in the bucket and lightly shake. If you can take out the finished product, congratulations, your design passes the bucket test!
Sam H
Manufacturing Business Consultant
"Excellent platform for prototyping & manufacturing"
Jiga is the best way to get the parts you need, when you need them.
Obtain or record guidelines of DFM for your company
If they do not already exist it can be very valuable to create detailed guidelines of DFM that cover the fabrication processes used by your company, both in and out-source. This will serve both as a checklist for your own future work and a convergence for the whole company to integrate a process and know that their contributions are heard and accommodated:
Understand your company’s in-house and out-source fabrication processes:
- List all the fabrication processes your company uses – machining, injection molding, sheet metal fabrication, welding, PCB making/populating, casting, additive manufacturing etc.
- Gather any existing process documentation, standard operating procedures (SOPs), and work instructions related to these processes.
Consult internal experts:
- Speak with the design, manufacturing, and process engineers who are familiar with the fabrication and assembly processes.
- Organize workshops or meetings to gather input and insights from experienced personnel. This collaborative approach ensures comprehensive guidelines that reflect the on-the-factory-floor practical knowledge.
Collect relevant data:
- Review previous projects to identify common challenges and successful practices in manufacturability.
- Examine quality reports and defect logs to understand frequent manufacturing issues.
Develop process-specific guidelines:
- Provide guidelines on selecting appropriate materials for each fabrication process, considering factors like supply chain reliability, processing needs, health and safety issues.
- Offer tips on designing parts that are easy to assemble, such as using self-locating features, standard fasteners, and minimizing part count.
- Specify acceptable tolerance ranges and fits for different fabrication processes to ensure parts fit together correctly without excessive adjustments.
Create visual aids and checklists:
- Use flowcharts and diagrams to illustrate key steps and considerations in each fabrication process.
- Develop checklists that designers and engineers can use to ensure they are following DFM principles for each fabrication process.
Incorporate industry standards and best practices:
- Refer to industry standards and guidelines relevant to your fabrication processes, such as ISO, ANSI, and ASME standards.
- Look at best practices from industry leaders and incorporate those that are applicable to your company’s processes.
Implement effective feedback loops:
- Periodically review and update the DFM guidelines based on feedback from the manufacturing floor, changes in technology, and new insights.
- Encourage a culture of continuous improvement where employees can suggest enhancements to the guidelines.
Documentation and distribution:
- Compile all the guidelines into a comprehensive DFM manual that covers all aspects of the fabrication processes.
- Ensure the guidelines are easily accessible to all relevant personnel through digital platforms like an intranet or document management system.
- Develop training programs to educate employees on the DFM guidelines and ensure they understand how to apply them in their work.
Example structure of DFM guidelines manual
- Introduction: Purpose of DFM guidelines: scope and applicability.
- General DFM principles: Minimizing part count: standardization of components: design for assembly.
- Process-specific guidelines:
Machining: material considerations: tolerance and surface finish: tool access and clamping.
Injection molding: mold design considerations: material selection: parting lines and ejector pins: gate suitability: draft angles: approach to side actions.
Sheet metal fabrication: bend radius and K-factor: hole sizes and distances: welding and joining techniques: approaches to tooling.
Additive manufacturing: layer thickness and orientation: support structures and removal: material and process selection: post-processing requirements
ETC as appropriate for your operations.
- Quality and inspection: key quality metrics: inspection techniques: common defects and mitigation strategies.
- Implementation and feedback: training and education: continuous improvement processes: feedback mechanisms
By structuring your guidelines effectively for the operations of your own business, you can ensure that your DFM guidelines are comprehensive, practical, and tailored to your specific needs.
Examples of good and bad DFM
Apple iPhone
- Minimized part count: The iPhone’s unibody construction reduces the number of parts, enhancing durability and simplifying assembly.
- Standardization: Uses standard screws and connectors, which simplifies assembly and maintenance.
- Design for assembly: Components are designed for easy alignment and snap-fit assembly, reducing assembly time and error.
LEGO bricks
- Standardization: All LEGO bricks are designed to be compatible with each other, regardless of the set, ensuring a perfect fit every time.
- High process capability: The precision molding process ensures consistent quality and fit.
- Simplified geometry: Simple, repeatable shapes that are easy to manufacture.
Dyson vacuum cleaners
- Modular design: Parts can be easily snapped together and taken apart, making assembly and repairs straightforward.
- Minimized adjustments: Designed to require minimal post-assembly adjustments, enhancing reliability.
- Ease of assembly: Components are designed for easy alignment and assembly, reducing production time.
Examples of Bad DFM in products
Early Xbox 360 (Red ring of death issue)
- Poor thermal management: Inadequate cooling design led to overheating issues.
- Non-standard components: Custom components that were difficult to source and replace.
- Assembly complexity: Design required intricate assembly processes, leading to higher failure rates.
Pepsi AM Can (1989)
- Overly complex packaging: The can design was difficult to produce consistently, leading to high manufacturing costs.
- Non-standard sizes: Deviated from standard can sizes, complicating production and logistics.
Apple Power Mac G4 Cube
- Complex assembly: The intricate and compact design made assembly and disassembly difficult, impacting repairability.
- Heat dissipation issues: Poor thermal management due to the compact design led to overheating.
- Custom components: Use of non-standard, custom parts increased production complexity and costs.
Examples of effective application of DFM principles demonstrate the benefits of minimized part count, standardization, ease of assembly, and modular design. These practices result in efficient, cost-effective manufacturing processes and high-quality products.
In contrast, bad DFM examples highlight the pitfalls of poor thermal management, overly complex designs, use of non-standard components, and difficult assembly processes. These issues lead to increased production costs, higher failure rates, and customer dissatisfaction.
Review how to optimize tolerances to enhance manufacturability
Optimizing tolerances is critical to enhancing manufacturability, as it directly impacts production costs, time, and quality. Here’s how to approach it:
Avoid over-specifying precision:
Benefits:
- Reduces manufacturing costs per component
- Simplifies the production process, potentially downgrades supplier/equipment needs
- Decreases inspection time and costs
Implementation:
- Determine the exact functional requirements of each part and avoid specifying tighter tolerances than necessary.
- Identify which areas of the part are critical to performance and which are not. Apply tighter tolerances in must-have areas.
- Perform a tolerance analysis to understand the impact of different tolerance levels on the overall assembly and function.
- In restricted conditions for stack-height apply tolerance allocation and derive material/process selections accordingly
Use standard tolerances, where practical:
Benefits:
- Eases expectation on suppliers
- Reduces lead times
- Lowers production costs
Implementation:
- Refer to industry standards (e.g., ISO, ANSI) for common tolerances in manufacturing.
- Utilize part libraries with predefined standard tolerances.
- Use standard components from supplier catalogs that already specify common tolerances.
Apply tolerances selectively:
Benefits:
- Focuses resources on critical dimensions
- Simplifies quality control
- Reduces waste
Implementation:
- Apply tight tolerances only to features that are crucial for the part’s function, assembly, or performance.
- Use broader tolerances for non-critical features to allow for easier and more accessible manufacturing.
- Incorporate functional testing to ensure that parts meet performance requirements even with broader tolerances.
Consider supplier/process capabilities:
Benefits:
- Ensures manufacturability within existing capabilities, select suppliers to suit tolerances rather than the other way round
- Reduces the need for special processes or equipment
- Enhances supplier collaboration and reduces production risks
Implementation:
- Consult with suppliers to understand their manufacturing capabilities and limitations.
- Align tolerances with the capabilities of the intended manufacturing processes (e.g., CNC machining, injection molding).
- Review process capability studies (Cp, Cpk) to determine achievable tolerances.
Communicate clearly:
Benefits:
- Prevents misunderstandings and errors
- Ensures that design intent is understood
- Facilitates smooth collaboration between design, manufacturing, and quality teams
Implementation:
- Provide clear and detailed drawings with all necessary tolerance information.
- Use geometric dimensioning and tolerancing (GD&T) to specify tolerances clearly and unambiguously.
- Include tolerance tables or notes in the documentation to clarify general and specific tolerance requirements.
- Maintain open communication with suppliers to address any questions or clarifications regarding tolerances.
Optimizing/relaxing tolerances is essential for enhancing manufacturability and controlling price by alleviating process upgrade pressures. A balanced approach ensures that parts are manufactured within acceptable limits without unnecessary precision that complicates the manufacturing process.
Summary of everything we have covered
This is a big topic, don’t expect to master it in one reading of a guide, however great this guide is!
The practical test is in the successes and disruptions you see in your progress from concept to mass production, and applying the learning that you gather as you go.
Obtain practical DFM feedback on your existing products or products under development.
Obtaining practical DFM feedback on existing products or those under development is the right way to validate the decisions that have been made, before they’re tied in by inertia and project delays/cost-ups.
- Conduct design reviews: Involve cross-functional teams, including design, engineering, manufacturing, and quality control, to evaluate the design.
- Engage suppliers: Collaborate with suppliers to gain insights on material choices, process capabilities, and cost implications.
- Prototype testing: Develop and test prototypes to identify and address manufacturability issues early.
- Pilot runs: Implement pilot production runs to gather real-world data on production efficiency and potential bottlenecks. Remember, an engineer pilot build before tooling is a great stage/gate evaluation at the final low-cost opportunity.
- Solicit operator feedback: Collect input from assembly line workers and technicians who interact directly with the product.
- Iterate in a timely fashion: Use feedback to refine the design, improve processes, and ensure the product is optimized for manufacturability before full-scale production.
How to analyze the manufacturability of your product
Analyzing the manufacturability of a product involves a comprehensive review and iterative process to ensure that the design can be efficiently and cost-effectively manufactured. Here’s how to approach it:
Design review with stakeholders:
Benefits:
- Identifies potential issues early
- Ensures alignment with business objectives and customer needs
- Leverages diverse expertise for better decision-making
Implementation:
- Multi-disciplinary meetings: Include representatives from design, engineering, manufacturing, quality, procurement, and marketing in the review.
- Structured review process: Follow a structured process such as Design for Manufacturability and Assembly (DFMA) checklists to systematically assess the design.
- Document feedback: Record all feedback and action items to ensure nothing is overlooked.
Material selection for ready availability and ease of processing:
Benefits:
- Ensures materials are readily available, reducing lead times
- Simplifies manufacturing processes
- Balances performance, cost, and manufacturability
Implementation:
- Supplier consultation: Work with suppliers to understand material availability and suitability for your processes.
- Standard materials: Prefer standard, widely-used materials over exotic or custom options.
- Material properties: Consider properties like machinability, moldability, durability, and cost in your selection process.
Process capability, limitations of available processes:
Benefits:
- Aligns design with the capabilities of existing manufacturing processes
- Reduces the need for special processes or equipment
- Ensures consistent quality and reduces defects
Implementation:
- Process assessment: Evaluate the capabilities of your current manufacturing processes, including tolerances, throughput, and costs.
- Manufacturing feasibility studies: Conduct feasibility studies to identify any limitations or challenges with the proposed design.
- Process selection: Choose manufacturing processes that can reliably produce the design within the specified tolerances and quality standards.
Tolerance analysis/optimization:
Benefits:
- Balances cost and manufacturing ease with functional requirements
- Reduces scrap and rework
- Ensures parts fit and function as intended
Implementation:
- Tolerance stack-up analysis: Perform tolerance stack-up analysis to understand the cumulative effects of part tolerances on the assembly.
- Process capability data: Use data from existing processes to set realistic and achievable tolerances.
- Adjust tolerances: Optimize tolerances to be as wide as possible while still meeting design requirements.
Cost evaluation:
Benefits:
- Ensures the product can be manufactured within budget
- Identifies cost-saving opportunities
- Balances cost with quality and performance
Implementation:
- Cost breakdown: Perform a detailed cost breakdown of materials, labor, overhead, and other expenses.
- Cost models: Use cost models to estimate the impact of design changes on overall product cost.
- Benchmarking: Compare costs with similar products or industry standards to identify potential cost-saving measures.
Prototype testing:
Benefits:
- Validates the design and manufacturing processes
- Identifies potential issues before full-scale production
- Provides insights into performance and reliability
Implementation:
- Functional prototypes: Create functional prototypes to test the design under real-world conditions.
- Pilot runs: Conduct pilot manufacturing runs to identify any production issues and validate process parameters.
- Testing protocols: Develop and execute testing protocols to thoroughly evaluate the prototypes.
Feedback integration:
Benefits:
- Continuously improves the product and manufacturing processes
- Ensures lessons learned are applied to future projects
- Enhances product quality and manufacturability
Implementation:
- Collect feedback: Gather feedback from prototype testing, pilot runs, and stakeholders.
- Document changes: Clearly document all changes and the rationale behind them.
- Iterative improvement: Use an iterative process to refine the design and manufacturing processes based on feedback.
Conclusion
Analyzing the manufacturability of a product requires a thorough review of the design, material selection, process capabilities, tolerance optimization, cost evaluation, and prototype testing, followed by the integration of feedback. An holistic approach ensures that the product can be efficiently and cost-effectively manufactured while meeting quality and performance requirements.
