Choose the Manufacturing Process
Part geometry should be compatible with the intended production method.
DESIGN FOR MANUFACTURING
Design Guidelines for Custom Manufacturing
Good part design starts with understanding how geometry, material, tolerances and manufacturing processes affect production. These practical design guidelines help engineers and buyers review CNC machined, die cast, injection molded and stamped parts before prototyping or requesting a quote.
QUICK DESIGN CHECK
Before You Send a Part for Manufacturing
Use this checklist to prepare the main design information before process review, prototype planning or quotation.
Select the Material
Material affects machining, forming, casting, molding and finishing options.
Identify Critical Dimensions
Separate truly critical interfaces from general dimensions.
Review Wall Thickness
Avoid unnecessarily thin or inconsistent walls where the manufacturing process is sensitive to them.
Check Holes, Radii & Corners
Hole depth, internal radii and corner geometry can affect tool access and manufacturability.
Define Surface & Assembly Requirements
Finishing, threads, inserts and mating interfaces should be identified before production review.
DESIGN BY PROCESS
Design Guidelines by Manufacturing Process
Each process has different design sensitivities. These cards summarize design considerations and route users to process pages for deeper manufacturing details.
CNC Machining Design Guidelines
Design decisions should consider cutting-tool access, internal radii, pocket depth, hole depth, thin walls and genuinely critical tolerances.
- Tool Access
- Internal Corner Radii
- Deep Pockets
- Hole Depth
- Thin Walls
- Critical Tolerances
Die Casting Design Guidelines
Cast part design should review wall consistency, draft, ribs, bosses, fillets and machining allowance before tooling decisions are made.
- Wall Thickness
- Draft
- Ribs
- Bosses
- Fillets
- Machining Allowance
Injection Molding Design Guidelines
Molded plastic designs should review uniform walls, draft angles, ribs, bosses, undercuts and parting or gate considerations.
- Uniform Walls
- Draft Angles
- Ribs
- Bosses
- Undercuts
- Parting / Gate Considerations
Metal Stamping Design Guidelines
Stamped and formed metal designs should consider bend geometry, hole placement, material thickness and secondary operations.
- Bend Geometry
- Hole-to-Edge Distance
- Bend-to-Hole Distance
- Formed Features
- Material Thickness
- Secondary Operations
PROCESS SELECTION
How Part Design Affects Process Selection
The manufacturing process should fit the part geometry, material, production requirements and critical features. Some designs are naturally better suited to one process, while others may require a combination of processes.
| Design Requirement | Processes to Review |
|---|---|
| Complex 3D geometry | CNC Machining / Die Casting / Injection Molding |
| Thin formed sheet | Metal Stamping |
| Internal pockets & precision features | CNC Machining |
| High-volume molded geometry | Injection Molding |
| Cast housing with secondary machining | Die Casting + CNC Machining |
| Brackets and formed structures | Metal Stamping |
Need help choosing a process? Review the Process Selection Guide.
GENERAL DFM PRINCIPLES
Design Decisions That Affect Manufacturability
Manufacturability depends on how wall thickness, internal radii, feature access, tolerances, threads and overall geometry interact with the selected manufacturing process. Reviewing these details early can make process selection, quotation and downstream inspection clearer.
Wall Thickness
Wall geometry can influence forming, casting, molding, machining strategy and part stability.
Internal Corners & Radii
Corner geometry affects tool access, molded or cast transitions and stress-sensitive areas.
Holes & Deep Features
Hole depth and feature access can affect machining sequence and inspection review.
Tolerances
Drawing-defined tolerances should be applied to features that matter for fit, function or assembly.
Threads & Inserts
Threaded features and inserts should be identified early because they affect downstream operations.
Part Size & Geometry
Overall size and feature relationships can influence process choice, tooling and handling.
TOLERANCE DESIGN
Use Tight Tolerances Only Where They Matter
Tighter tolerances can increase machining time, inspection requirements and manufacturing cost. Instead of applying the same tolerance across the entire part, identify the dimensions that directly affect fit, function and assembly.
Mating Surfaces
Interfaces that contact another component may need drawing-defined tolerance review.
Bearing / Shaft Interfaces
Rotating or locating features should identify fit and functional requirements clearly.
Hole Position
Hole patterns can affect assembly alignment and inspection planning.
Assembly Features
Features used for fastening, locating or mating should be separated from general dimensions.
GEOMETRY DESIGN
Keep Geometry Practical for the Manufacturing Process
Geometry should support the selected manufacturing route while preserving the functional purpose of the part.
Thin Walls
Design Risk
Thin walls can increase deformation or process sensitivity depending on material and manufacturing route.
Better Approach
Use wall thickness appropriate to the selected process and only reduce thickness where the functional design requires it.
Deep Pockets
Design Risk
Deep, narrow pockets can reduce tool access and increase machining complexity.
Better Approach
Where possible, increase access, reduce unnecessary depth or review alternative geometry.
Sharp Internal Corners
Design Risk
Very small internal radii may require smaller tools and longer machining time.
Better Approach
Use practical internal radii where the design allows.
Long Slender Features
Design Risk
Long, thin or unsupported features can be more sensitive during machining, forming or handling.
Better Approach
Review feature thickness, support and process selection according to function.
FEATURE DESIGN
Design Holes, Threads & Features for Manufacturing Access
Features should be reviewed for manufacturing access, secondary operations and inspection clarity.
Hole Depth
Deep holes should be reviewed for access, sequence and inspection requirements.
Thread Depth
Thread requirements should be communicated on the drawing and reviewed against function.
Hole-to-Edge Distance
Hole placement can affect strength, forming sensitivity or available machining access.
Tool / Mold Access
Feature orientation and access can affect the manufacturing route and secondary operations.
MATERIAL & DESIGN
Material Choice Changes the Design Rules
Material can influence machining behavior, forming sensitivity, wall geometry, surface finishing and structural requirements.
Aluminum
Often reviewed for machined housings, brackets, enclosures and parts needing finishing options.
Stainless Steel
Often reviewed for strength, corrosion resistance and machined features with defined interfaces.
Carbon Steel
Often reviewed for structural, stamped, formed and machined components according to drawing requirements.
Engineering Plastics
Often reviewed for molded or machined functional components, covers, guides and insulating parts.
SURFACE FINISHING
Consider Surface Finishing During Part Design
Finishing requirements can affect dimensions, masking, threads, mating areas and appearance-sensitive surfaces.
Masking Areas
Areas that should not receive finish should be identified before production review.
Mating Surfaces
Functional interfaces may need review before coating or plating is selected.
Threaded Features
Threads can require special attention when finishing is applied after machining.
Appearance Surfaces
Visible surfaces should be defined separately from general functional areas.
DRAWING & CAD CHECKLIST
What Should Be Clear on Your Drawing?
A 3D model defines geometry, but the 2D drawing should communicate requirements that are not fully represented by geometry alone.
Critical Dimensions
Identify dimensions that affect fit, function and assembly.
General Tolerances
Define default tolerance expectations separately from critical features.
Material
Specify material category and requirements needed for review.
Surface Finish
Communicate finish, appearance and masking requirements.
Threads
Define thread type, location and functional needs.
Inserts
Call out inserts or hardware when required for assembly.
Mating Interfaces
Identify features that must align or locate with other parts.
Inspection Requirements
Clarify features that need specific inspection review.
COMMON DESIGN ISSUES
Common Design Issues That Can Increase Manufacturing Complexity
These review points are neutral engineering checks. The goal is to make requirements easier to manufacture, inspect and quote.
Overly Tight Tolerances
Why It Matters
They can increase setup, manufacturing control and inspection requirements.
Better Review Direction
Apply tight requirements only where fit, function or assembly needs them.
Difficult Tool Access
Why It Matters
Limited access can increase setups, tooling complexity or secondary operations.
Better Review Direction
Review feature orientation and manufacturing access early.
Unclear Critical Requirements
Why It Matters
When critical and general requirements are not separated, quotation and inspection planning can become less clear.
Better Review Direction
Identify the features that directly affect fit, function and assembly.
Unclear Datum / Interface Requirements
Why It Matters
Unclear locating or mating references can make dimensional interpretation and inspection planning more difficult.
Better Review Direction
Define the relevant datum, mating surface or interface relationship on the drawing where required.
Unnecessary Secondary Operations
Why It Matters
Extra machining, finishing or hardware operations can add process steps without improving part function.
Better Review Direction
Separate required operations from optional features during design review.
Unmarked Appearance Surfaces
Why It Matters
If visible surfaces are not identified, finishing and inspection expectations may be unclear.
Better Review Direction
Mark appearance-sensitive areas separately from general functional surfaces.
FROM DESIGN TO RFQ
Ready to Review Your Part Design?
Once the main geometry, material and manufacturing requirements are defined, the next step is to prepare the drawing package and RFQ information for review.
Send Your Drawing
2D drawing + 3D model
Review Manufacturing Requirements
Material, geometry, critical features and intended process
Prepare the RFQ
Quantity, finishing, inspection and project-stage requirements
FAQ
Design for Manufacturing FAQs
Common questions about preparing drawings, geometry and manufacturing requirements before quotation.
What is design for manufacturing (DFM)?
Design for manufacturing means reviewing geometry, material and manufacturing requirements so a part can be produced more efficiently and reliably.
How do I choose the right manufacturing process for my part?
Process selection depends on geometry, material, quantity, feature requirements and downstream operations such as finishing or secondary machining.
Why do tight tolerances increase manufacturing cost?
Tighter tolerances can increase setup, machining, process control and inspection requirements. Critical tolerances should be applied where fit, function or assembly requires them.
How should I design internal corners for CNC machining?
Practical internal radii can improve tool access where the functional design permits. Very small internal radii may require smaller tools and longer machining time.
Should I provide both a 2D drawing and a 3D model?
A 3D model defines geometry, while a 2D drawing communicates dimensions, tolerances, material, surface finish and other requirements that may not be fully represented by geometry alone.
Can FSD review my drawing before quotation?
Yes. FSD can review available drawings, CAD files and project requirements before quotation.
Related resources: Manufacturing FAQ and Blog.