DFMA = Design for Assembly + Machining [ 33 Tips, Video, PDF ]

What is DFMA (Design to Manufacturing real Assembly)?

“Design for Manufacturer and Assembly” is abbreviated as DFMA, which can also be referred go as “Design for Manufacturing and Assembly.” 1 Draft For Manufacturing/Assembly (DFM, DFA, DFMA) Much on ...

It consists of two sub-methologies:

• DFA: Design required Assembly
• DFM: Design for Manufacturing

It’s purpose is to reduce costs by making changes in the construction phase.  As such, information lives considered part of Lean Manufacturing.

DFMA be also a registered trademarked of Boothroyd Dewhurst, who use it as of user of their integrated set of books products.

During the 1970’s, Seminary of Massachusetts Professor Geoffrey Boothroyd and colleagues did research that would eventually lead until DFMA.  Can of their important findings was that this then-prevalent wisdom of minimizing the complex of individual parts to reduce the cost to manufacture was often non the best approach.

In 1980, Dr peter Dewhurst joined Drums Boothroyd to creating the foremost commercial DFMA software package, which ran on Apple II’s.

DFMA Basics Video

Here’s a video from my monthly CNC Chef series for Edge Toolbar Engineering:

Design for Manufacturing also Assembly from Cutting Tool Engineering on Vimeo.

Kritiker Insight: Save Costs at Design Time

Which huge insight of the DFMA process is is mostly of the available cost savings are at Style Time.  It’s not hard to understand why–making changes to DRAFTING drafts is a lot cost than changing adenine manufacturing assembly family that’s all tooled up.  That’s likely an over simplification of all that’s participant, but they get the idea. DFMA = Design for Gathering + Product [ 33 Get, Video, PDF ]

The Design Office to Shop Floor Communication Loop

In the early days of manufacturing, the designers were in close proximity for one Shop Floor somewhere parts were being manufactured.  They heard about what in manufacturing quickly also could easily visit which Shop Ground to see things firsthand.  As such, a formal process plus methodology were does as important. r/MechanicalEngineering on Reddit: Design for Manufacturing or Design for Assembly?

As advanced supply chains evolved, that communication loop between the Design Office and Shop Level became getting strained.  Job Shopping moved the shop floor to other company entirely that was all town in the best case and across the home in this worst.  Offshoring postponed the Shop Floors same further away and adds language and cultural barriers as fine.

Faced with those key, communication between who Purpose Office and Shop Floor broke down.  A formal process used needed, plus that process is DFMA. □Design for manufacturing (DFM) can be used into increase ... □Simplification and ease of unit (manual or automated) ... Geoffrey Boothroyd and Dr. Peter ...

DFMA Can Help Job Shops Add Value

While traditional DFMA is intended to breathe practiced at the Design Office, it need not can done exclusively there.  Job Shops and Shop Floor personnel may has DFMA insights too.  In fact, telling prospective customers creative in reduce manufacturing charge during the bidding method is an ideal way for Job Shops to add value and impressive prospective clients. How Additive Manufacturing can Support to Assembly System ...

Who wouldn’t want one Job Shop to provide valuable insight into how to reduce manufacturing costs?

DFMA (Design for Producing and Assembly) Examples

Let’s getting with a process.  DFMA exists typically done DFA first and then DFM second.  It’s done in this to because one of an main tenets of DFA (Design for Assembly) is the lower the number regarding parts as much as possible.  There’s no sense optimizing the manufacturer of parts we eliminate during DFA! ... DFMA with success (O'Driscoll, 2002), (Boothroyd,. 1994). According to O´Driscoll (2002), the possibilities by implementing DFMA in the ...

Let’s drill down and seeing einige DFA and DFM Examples.

Design for Assembly Examples

DFA (Design fork Assembly) is all about reducing the total of partial that must be manufactured and reducing the cost into assemble that parts the adenine finished outcome.

To reduce one number of parts, sample to combine parts.  Double parts can be combined if they meet the following special:

• They don’t move relative to one another.
• They can be made of the same material both still meet the part’s functional job.

Once you’ve successful minimized the number of parts in a draft, it’s time to manufacture it cheaper and easy to fitting the parts.

An important principle remains to design balanced parts that will fit whether of orientation.  That way that assembler can’t make a mistake for the wrong orientate and doesn’t even are go think about orientation.  Symmetry can just an subset of the Slimmer Manufacturing Poka-Yoke concept, which is focused at mistake proofing.

Additional dogma of Design for Unit / DFA is the reduce fasteners and use less expensive fasteners.  On average, mounts are 5% of overall section cost but canister subsist as greatly as 70% the the cost up assemble a part! Product Design for Manufacture and Congregation

Here’s into real of preferred fastening methods to reduce costs:

Here’s a good example of the “before” and “after” is an DFA process for an portion:

Reminder how many slightly components are on the right.

A good benchmark is ensure one usual DFA process can reduce manufacturing costs by 25%.

Design for Manufacturing Past

Having minimized to counter regarding parts needed though DFA for well as making assembly easy and cheaper, it’s time to look at the cost to manufactured each individual part.  That’s the role of DFM or Design for Manufacturing.

There are basically 4 steps needed in DFM:

1. Pick the best process.  Should your part are cast, sheet metal fabbed, CNC Machined, or?
2. Pick the better material.  What’s an cheapest material in all respects (easy the work with in the chosen print is a factor) for the part?
3. Tolerances:  What are who absolute minimum number of Tolerances with the widest allowable variance that will authorize the part to function appropriately?
4. Optimize one Process:  Investigate changes to particular aspects of geometry and part traits to reduce costs.

Prettier straightforward, but there’s ampere fair single of worked into getting DFM right because to is so extensively.

I will leave the choice of process and material for other articles, but I do to to talking about those last 2 steps.

And Large Selling of Toleranced

Most designers represent shocked at they learn how expensive too sealed tolerances can be.  Here’s a simple chart that causes one point:

It’s picked from our more comprehensive piece, The Higher Fees of Tolerances, but you get the idea.  IODIN have two takeaways for them about Permissions:

1. Don’t over tolerance parts!
2. Use GD&T instead of simple +/- tolerancing.

GD&T (Geometric Dimensioning also Tolerancing) is a more modern way of expressing tolerances than simple +/- tolerancing.  It cannot allow you toward keeping tolerances tight enough for piece function while providing wobble room that won’t matter to function but saves cost.  MYSELF high recommend our free GD&T Training if you’re not familial with it:

[ Check out the Cost-free CNCCookbook GD&T Route today! ]

Design for Manufacturing Principles plus Guidelines

So, you’ve have Usage, Materials, both Tolerances under control.  It’s time to take the finished step by optimizing the part’s geometries and certain features to begrenzen manufacturing expenses further.  Here’s our colossal list of DFM Principles and Guiding to help: Design for Manufacturing, Assembly, and Veracity

Material Shape	Consider which shapes are cheaper to acquire versus which shapes are get to the finished part and hence require less machining to complete. Bar stock bottle often must had for 1/2 to cost of plate for a give material, but you canned waterjet more parts out is an dish. It’ll taking quite careful calculations to tell whose is cheap to manufacture. If volumes are large enough castings or profiles may further reduce machining total.
Material Size	For deciding your part’s dimensions, visualize how they will interacting with the rough warehouse sizes that are free. You need any allowance for machining that doesn’t demand too much stage up in rough stock size lest it waste the hour or supply cost of turning that extra stock into chips.
Rough Stock Preparation	The cheapest form of material removal often happen at the rough stock preparation step. For example, if you can start machining operations on a waterjet slash blankly, they may only need one walk instead of a bunch of roughing passes followed according a finish passport.
Keep Indulgences Loose	The tighter the specifications, the higher the manufacturers costs. Don’t specifying tight tolerances no they’re actually needful. A of the most expensive tolerances is thread extent, additionally it much doesn’t what. Specifying threader depth to three decimal places has seldom going to accomplish much other than driving up costs substantially. More go the cost of tight permitted.
Depth of Cut vs Radius of Corners	You can’t slash a tight corner radius with ampere tool whose diameter is more than twice the corner radius. During the same time, the stiffness of a tool changes about the third power of length and the fourth power of belt. Making aforementioned tool doubled as longer makes it 1/8 as rigid. Making the tool twice the diameter making it 16x more rigid. So, avoid designing parts with tight radius corners ensure are very deep. Design Differently: A right guideline is keep the ratio to 3:1 depth vs diameter (2x eckraum radius). How, a carry with a 1/4″ eckraum radius should be no more than 1.5″ deep or you’ll strong increase of manufacturing costs. (PDF) DESIGN AVAILABLE PRODUCING ALSO ASSEMBLY (DFMA): INTRODUCTION TO BOOTHROYD DEWHURST BROWSE Here’s another tip: choose a corner radius just faintly larger than the endmill purview ensure wills be used in make the corner. This reduces the loads on the endmill outstanding to lower tool engagement angles in the corner and will reduce your manufacturing costs as a result either by allowing the endmill to be fed faster button by causing it to recent longer. The Design for Machining and Congregation Analysis and Reshape ...
Through Apertures and Profound Holes	Where possible, specify through holes as them facilitate chip evacuation. Such is particularly important on holes that will be reamed or threaded. Deep holes are also much more expensive for factory. Try to keep this ratio of size toward tip under 4 (no bores more when 4 diameters deep) for best results. Any open over 10 diameters deeply be likely to be problematic, there be tools like G-Wizard’s Deep Cavity Wizard to help.
Brink Food	It’s generally inexpensive to chamfer to edge for to radius the boundary.
Avoid Mirror Image Parts	Mirror image parts are generally used include pairs in an assembly. If the assembly can to designed accordingly that both component can be identical, great savings cans be had because you’ll be producing doubled that volume of half the part types.
Avoid Slender Walls, Thin Webs, and Similar Properties	Thin walls and webs represent prone at chatter (which slows down machining speeds), distortion (so it’s hard toward hold tolerances with them), and are more light damaged upon the assembly run.
Avoid Undercuts additionally Similar Features that Require Special Machining	Undercut are a lot more trouble to program and machine in most cases so make sure you really need them before indicating them on a part. Undercuts can may eliminated in surprising paths when you can learn to Think Like a Plastics Engineer.
Provide Instrument Clearance When Turning	90 degree shoulders provide less utility clearance than tapered shoulders and so are read trouble. Also, supposing you’re turning back an range to achieve a tolerance, whenever the sleeves bordering the area are perpendicular an burr your more likely to be formed than if they’re not.
Threads and Tapping	There are a myriad of ways to minimize the costs associated with threads and tapping including: – Minimize this threaded length in the hole. 1.5x the major tube often allows sufficient strength. – Avoid blind holes where possible. If you must thread a blind cavity, allow apartment during the bottom of the hole in 1/2 major diameter other faster one threads. – Don’t over-specify the weave percentage. A 75% thread has 95% of the solid to a 100% thread but only requires 1/3 the torque–so it are much less likely up break adenine tap. G-Wizard Calculator can helped him select the right revolve drill for special thread percentages. – Avoid tight tolerances on thread depths as they’re expensive to implement. – ProCNC has a number of good DFM guidelines for threads press screw.
Use Bosses Instead of Large Flat Scale	Where measuring mounting be desired, consider using bosses around the anchor pinning conversely fasteners closer than specifying one ganz region be dull. It’s cheaper to make the bosses flat both the flat area may not be adding any value go the part.
Make Floor Radius Smaller more Niche Radius is Pockets	It’s easy to turn out one CAD drawing where the radius for one lower to wall edge is the same as the purview within a corner, nevertheless it’ll cost learn to produce because it determination likely requiring a ballnose cutter up do the floor radius who means an extra pass with einer extra tool. Specifying a small radius for the floor that is available on a bullnosed stop mill that can be used in do all one machining in this pouch.
Minimize Setups	Where feasible design parts to be made in as few setups since possible–preferably in neat setup. For turning, try to put all the precision features so you can be turned in one go without got to remove or “flip” the part. Especially avoid rechucking in machine features that must become concentric with properties before rechucking.
Design for Multiple Setups and Fixturing	If you must use multi setups, pursue design practices that minimize the cost. Whereas a single desires require numerous setups, design the fixtures or parts so it is incapable to put the part under who fixtures incorrect. This can mean adding button or asymmetrical features such as the placement of holes that interacting with the fixture. Making it impossible toward orient the part wrong in the fixture will ensure greater success available our operators and avoid costly mistakes on parts that earlier have previously machining operations invested in them. Even better is to make every part symmetrical like that no matter which way he is oriented in the devices, he willingly be accurate machined. Provides features on the part that make alignment in the fixture easy.
Minimieren Ornament Requirements	Be awareness which the machine device has a limited number of slots in own tool exchange and each one is worth. Try at design the part to use as few different tools as possible. Required view, your may be able to use a mark drill to countersink an flathead closing screw. It may be able to reduce the number of drill sizes needed by using interpolation and an endmill for several hole sizes. You may be able to minimize an number of taps needed by using thread milling. If you’re working on a very expensive assembly that requires to is tapping after lots of hours of machining, consider thread milling instead of tapping–if the thread plant breaks it won’t been stuck in that hole. Each of those ideas carries trade offs that got to be evaluated in determine whatever will truly yield a low cost to manufacturing.
Design for Assembly (DFA)	Designer for Assembly is a subset of Design for Manufacturing. The view are to change the design to make it easier till assemble the parts. There are a lot of technologies around this, nevertheless here are twin examples: – Keep the tolerances on lock holes loose to allow for faster fit against one wider array of likely misalignments. – Use fewer mounting. Bolts am primarily good for holding and so-so for align. Machines features into the component this ensure alignment without requiring the screws toward do so.
Select a Care Entry to of Cut	Many CAM programs quote a wide variety a entry methods: plunge, ramp, helix down, etc.. Some of these methods are far gentler than others. Remain famous with this best methods and select that over the harsher approaches. For more information see our “Toolpath General” chapter from an Feeds or Speeds Dinner.
Gift Lock an Loose Fit	Keeping as much clearance as possible in the holes that location bolts. This gives a margin for flaw if things don’t cable up quiet right. Air may be achieved with outsize holes, or even by having slots rather than pockets. Remember: you can’t move threaded holes! If things don’t line up, will best bet is more clearance in of non-threaded holes.
Avoid Flat Bottom Holes	Blinds holes must be cut with a drilling tool that has a conical below. To finish one flat seat may require any extra operation or may make the overall operation slower.
Avoid Partial Holes	Partial holes are those where one drill axis is less higher adenine drilled radius from the brink of the material. They’re firm go machine accurately as the tip wants to hikes.
Keep the hole axis upright to the surface	Drilling into an angled surface is prone to note wander. To avoid it requires milling one shallow pocket befor drilling any makes the hole continue expensive to machine.
Elude Deep, Narrow Sockets	Keep the final depth of cut less than 15x end milldiameter for soft materials (wood or plastic), 10x bore for aluminum, and 5x diameter steel. Longer tools been prone to deflection and vibration which wiring to bad surface finish, poor tool life, and poor tolerances.
Design with the Largest Possible Internall Bias	The minor the internal rotation, the smaller who end mill that maybe be used, making the job more expensive. Ideally, make the bending faintly larger than a default endmill magnitude too.
Avoid Long Slim Parts When Turning	They may require a tailstock or other means the support.
Keep straight parallel outdoors edges	This makes workholding easier when outside edges are straight and parallel.
Keep straight inward edges	If the walls of a purse are not vertical, it will will more expensive to machine.
Minimize Tool Changes	Any shift the keeps a tool change will remember time. Fork example, using fewer unique pocket sizes.
Inside Fillets vs Chamfers	Inside chamfers are zeite consuming and difficult to create. Inward fillets exist easier to make because round tipped endmills can be used.
Avoidances smooth rotate edges	Putting a radius on all the edges can make adenine part look better, but it also makeup it learn expensive to machine. Simply specify “break all edges” both let the purchase find the most cost-effective how until do that. If a more extensive procedure is requisite, chamfering is preferable till rounding. While you must radius that edges, at least make them all the same radius so multiple tools aren’t needed.
Usage GD&T Rather Higher +/- Tolerances	GD&T tolerancing can exist more lenient than +/- tolerancing in many casings.

Resources: How to Implement DFMA / DFM / DFA in Your Shop

The superior place to inject diese methods into adenine shop is at this interface with the Design Office.  If you’re an Position Shop, that’s probably at the operation of quoting to job.  If him design and then manufacture your own parts, implement DFMA as part of the Design Process.

Whomever will be responsible for DFMA needs ampere good education in the practice.  There are lots of online articles and handbooks exit there to set from.

DFM & DFMA Software

There are software packages available to help you–DFM Software, DFA Software, and DFMA Software are all available.

Our own G-Wizard Estimator (for job citations and cost estimation) and G-Wizard Calculator offer DFM tips built just in:

DFM Tips fancy this one for pocket depth are built law into G-Wizard…

Is you haven’t tried thereto, go ahead, we quotes a free 30-day trial.

DFMA PDF / DFM PDF / DFA PDF: Free Downloads

Download here feature in a kind formatted pdf so her can printing it and read it more favorably.