DFMA: SHOULD COSTING
DFMA: PRODUCT SIMPLIFICATION
What is manufacturing process selection?
Manufacturing process selection is the engineering decision of which production method—injection molding, die casting, machining, forging, sheet metal, extrusion, or other process—to use for a specific part. It is typically made early in product development, at concept or preliminary design stage, because the process choice determines allowable tolerances, geometry constraints, cost economics, and production volume breakpoints.
The fundamental question is: which process minimizes cost while meeting all design requirements? The answer depends on five critical criteria: production volume, part geometry, material requirements, tolerance and surface finish, and the target cost. Different processes excel at different combinations of these factors. Injection molding dominates high-volume plastic parts. Die casting is unmatched for high-volume aluminum and zinc parts. Machining is the only option for complex, low-volume metal parts. Forging delivers highest strength. The framework in this guide helps you evaluate these trade-offs systematically.
This guide connects you to 15 different manufacturing processes, explains when each is economical, shows how to compare two processes head-to-head, and links to detailed cost estimators for each process family. It is the hub that connects all process-specific pages in the DFMA resources.
On this page
Why manufacturing process selection matters
Manufacturing process selection is one of the highest-leverage decisions in product development. The process you choose determines the minimum unit cost, the production volume at which the process becomes economical, the tolerances and surface finishes you can achieve, and the design constraints you must work within.
- Cost targets: set realistic targets by understanding process economics at your volume
- Design to cost: iterate toward targets with process-based cost feedback
- Make vs. buy: compare internal production cost to supplier quotes, process by process
- Global sourcing: compare cost in different regions, accounting for labor and overhead differences
- Design constraints: understand what geometries, tolerances, and materials each process allows
- Design team makes geometry decisions without cost visibility
- Cost overruns discovered in first supplier quotes—too late to recover
- Supplier negotiations become arguments about price, not about cost drivers
- Cost targets are set top-down without engineering basis
- Design is optimized for the wrong manufacturing process
The five selection criteria
Manufacturing process selection involves evaluating your part against five key criteria. All five must be considered together. No single criterion is decisive in isolation.
Annual or lifetime unit quantity. Determines economies of scale and tooling amortization. Different processes are economical at different volumes: machining has no tooling cost (best for low volume); injection molding requires 5k-10k units to amortize tooling; high-volume stamping requires 50k+ units; hand-laid composite layup is always low-volume; sand casting spans 1 to millions.
- 1–100 units: machining, hand layup
- 100–5k: investment casting, machining
- 5k–50k: injection molding, sand casting, forging
- 50k–1M: die casting, injection molding, stamping
- 1M+: high-speed injection molding, roll forming
Complexity, presence of internal voids, undercuts, thin walls, internal features. Some processes are geometry-flexible (molding, casting); others have strong constraints (forging, stamping). Undercuts can be molded; they require secondary machining if cast. Thin walls are easier to mold than to cast or forge.
- Simple extrusions: sheet metal, extrusion
- Complex, hollow shapes: injection molding
- Internal voids: molding, casting
- Undercuts: molding, investment casting
- Thin walls: injection molding, blow molding
- Thick, solid sections: forging, ductile casting
Strength, weight, thermal properties, corrosion resistance, electrical properties, surface properties. Not all materials work with all processes. High-strength alloys often require forging or precision machining. Polymers require molding or extrusion. Non-ferrous metals favor casting or die casting.
- Plastics: molding, extrusion, blow molding
- Aluminum/zinc: die casting, extrusion
- Steel/stainless: forging, casting, machining
- Powder metallurgy: for porous components
- High-strength: forging, precision machining
- Composites: hand layup, filament winding
Precision and smoothness required by the design. Some processes are inherently precise (machining, die casting); others require secondary finishing (sand casting, forging). Tighter tolerances increase cost. Specifying looser tolerances where possible is the highest-impact DFM opportunity.
- Loose (±1-5%): sand casting, forging
- Moderate (±0.1-1mm): die casting, injection molding
- Tight (±0.05-0.1mm): machining, precision casting
- Very tight (±0.01mm): precision machining
- Surface: Ra 3.2–6.3: molding; Ra 0.4–1.6: secondary finishing
Maximum allowable manufacturing cost at the target volume. This is often a constraint rather than a free choice. Once cost target is set, it narrows process options. A $2 piece-part cost at 100k/year requires either high-speed injection molding or die casting, not machining or hand assembly.
- Evaluate process unit cost at your volume
- Include tooling amortization
- Account for labor rates in your region
- Compare cost vs. required tolerances
- Set targets before detailed design locks geometry
The best process for your part is the intersection of all five criteria. A process might be perfect on volume and material, but geometry constraints rule it out. Another might work on geometry and cost but require material grades unavailable. Use these five criteria to shortlist candidate processes, then evaluate each candidate with detailed cost models.
The 15 manufacturing process families
DFMA offers process-specific cost estimators for 15 different manufacturing processes. Below are the process families, typical volume ranges, and links to detailed cost analysis for each. Use the links below to evaluate specific processes for your part.
Plastic & Polymer Processes
High-volume plastic parts. Volume range: 5k–1M+ units/year. Excellent for complex geometries, undercuts, internal voids. Low piece cost at high volume.
Hollow plastic containers. Volume: 10k–1M+. Bottles, tanks, large hollow parts. Low tooling cost for simpler cavities.
Thin-walled plastic parts. Volume: 1k–500k. Lower tooling cost than injection molding. Visible draft angles, thicker walls.
Linear profiles and sheets. Volume: 100k–10M+. Pipes, profiles, tubing. Continuous process. Very low piece cost at high volume.
Large, lightweight plastic parts. Volume: 1k–100k. Cellular structure reduces weight and cost. Thicker walls than injection molding.
Metal Casting Processes
High-volume aluminum, zinc, magnesium parts. Volume: 50k–1M+. Tight tolerances, good surface finish. High tooling cost; low piece cost.
Large, complex metal castings. Volume: 1–100k. Low tooling cost. Loose tolerances (±1-5%). Requires secondary machining for precision.
Complex, precision metal castings. Volume: 500–100k. Best surface finish (Ra 3–6). Near-net-shape, complex internal passages.
Metal Forming & Forging
High-strength metal parts. Volume: 10k–500k. Superior strength-to-weight. Tight tolerances, simple geometry. Second op machining often required.
Thin-walled steel, aluminum parts. Volume: 50k–1M+. Bends, cutouts, simple 3D. Low tooling for progressive dies at high volume.
Linear aluminum profiles. Volume: 10k–1M+. Moderate tooling. Complex cross-sections. Weight reduction vs. machining.
Precision & Subtractive Processes
Low-volume, precision parts. Volume: 1–10k. No tooling cost. Highest precision (±0.01mm). Expensive piece cost. Best for complex, low-volume.
Porous, permeable, or high-density parts. Volume: 10k–1M. Sintering process. Minimal scrap. Specialized material properties.
Complex, small metal parts. Volume: 10k–1M. Sintering process. Complex geometry, good precision. Bridges gap between machining and molding.
Electronics & Assembly
Printed circuit board assembly. Volume: 1–1M+. Board fabrication, component placement, soldering. Multiple cost drivers: board complexity, component count, assembly method.
Volume-based selection matrix
Different manufacturing processes are economical at different production volumes. This table shows the volume ranges where each process becomes cost-competitive. Use this to identify candidate processes for your part volume. For detailed cost comparison, follow the links to process-specific cost estimators and comparison pages.
| Process | 1–1k units | 1k–10k units | 10k–100k units | 100k–1M units | 1M+ units |
|---|---|---|---|---|---|
| CNC Machining | â– Best | â– Good | â– Expensive | â– Very expensive | â– N/A |
| Investment Casting | â– Marginal | â– Good | â– Good | â– Marginal | â– N/A |
| Sand Casting | â– Good | â– Good | â– Good | â– Fair | â– N/A |
| Forging | â– N/A | â– Fair | â– Good | â– Good | â– Fair |
| Injection Molding | â– N/A | â– Fair | â– Best | â– Best | â– Best |
| Die Casting | â– N/A | â– N/A | â– Good | â– Best | â– Best |
| Sheet Metal Stamping | â– N/A | â– Marginal | â– Good | â– Best | â– Best |
| Metal Extrusion | â– N/A | â– Fair | â– Good | â– Best | â– Best |
| Plastic Extrusion | â– N/A | â– N/A | â– Fair | â– Good | â– Best |
| Powder Metallurgy | â– N/A | â– Fair | â– Good | â– Good | â– Fair |
| Metal Injection Molding | â– N/A | â– Fair | â– Good | â– Good | â– N/A |
| Thermoforming | â– Fair | â– Good | â– Good | â– Fair | â– N/A |
| Blow Molding | â– N/A | â– Fair | â– Good | â– Best | â– Best |
| Structural Foam | â– N/A | â– Fair | â– Good | â– Fair | â– N/A |
| PCB Assembly | â– Fair | â– Good | â– Best | â– Best | â– Best |
Legend: Best = process is cost-competitive and widely used at this volume; Good = process works well at this volume; Fair = process is marginal, other options preferred; Marginal = process is less economical than alternatives; N/A = process is not practical at this volume (tooling cost too high, or insufficient volume to justify setup). Specific cost depends on part complexity, material, and regional labor costs. Use process-specific cost estimators to evaluate your part at your volume.
Material-based process selection
Material choice often narrows process options significantly. Not all materials work with all processes. Use this guide to identify which processes are appropriate for your material family.
Metal Parts
- Die Casting: high volume, tight tolerances, complex geometry
- Metal Extrusion: profiles, profiles, complex cross-sections
- Machining: low volume, highest precision
- Forging: high strength, medium volume
- Sand Casting: large parts, low-medium volume
- Forging: high strength, bars, shafts, medium-high volume
- Machining: low volume, precision, complex geometries
- Sand Casting: large, complex castings
- Investment Casting: complex, precision, medium volume
- Sheet Metal: stamping, forming for thin-wall parts
Plastic & Polymer Parts
- Injection Molding: primary choice for high volume
- Extrusion: profiles, linear parts
- Thermoforming: thin-wall, lower tooling cost
- Machining: low-volume prototypes, tight tolerance
- Hand layup: low volume, large parts
- Filament winding: cylindrical, hollow parts
- Injection molding: some thermosets (phenolic, epoxy)
- Resin transfer molding (RTM): medium volume
Specialty Materials & Processes
- Powder Metallurgy: sintering for custom density
- Metal Injection Molding (MIM): complex, small parts
- PCB Assembly: surface mount, through-hole, mixed
- Injection Molding: plastic housings and enclosures
Head-to-head process comparisons
When you have narrowed your process candidates to two or three options, use a head-to-head cost comparison to see which is best for your part. The pages below provide side-by-side analysis, cost breakdowns, volume breakpoints, and design trade-offs for the most common process comparisons.
How to use comparison pages: Select the comparison most relevant to your part and volume. Review the cost breakdown to understand which process is cheaper and why. Pay attention to volume breakpoints—the volume at which one process becomes cheaper than another. Use these pages to justify process selection to stakeholders and to identify design changes that would make one process more economical than another.
How DFMA automates process selection
DFMA contains process-specific cost models for 15 different manufacturing processes. Each model estimates cost based on the geometry, material, volume, and tolerance requirements you specify. Rather than consulting supplier quotes or industry benchmarks, DFMA builds transparent, first-principles cost estimates that show you exactly what drives cost and how to optimize it.
- Material cost and scrap/utilization
- Primary process cycle time and rates
- Tooling cost and amortization
- Setup and fixture costs
- Secondary operations (finishing, inspection, test)
- Volume-dependent economies of scale
- Regional labor and overhead rates
- Multi-process comparison: estimate same part in 15+ processes side by side
- Volume sensitivity: see how cost scales as volume changes
- Design-to-cost: change a spec and see cost impact instantly
- What-if analysis: compare processes, materials, regions, tolerances
- Supplier negotiation: benchmarks based on transparent, defensible cost drivers
Next step: Schedule a demo with the DFMA team. Bring your part CAD and we will estimate cost in multiple processes, show you the cost drivers, and explain how design changes move each component.
Frequently asked questions
What is manufacturing process selection?
Manufacturing process selection is the engineering decision of which production method to use to manufacture a part. It is one of the highest-leverage cost decisions in product development. The right process choice can cut manufacturing cost in half compared to the wrong process. Process selection typically happens at concept stage or preliminary design, when cost targets are set and design is still flexible enough to be optimized for the chosen process.
When should process selection happen in product development?
Process selection should happen as early as possible, ideally at the concept or early preliminary design stage. This is because 80% of manufacturing cost is locked in by design decisions, and process choice is one of the most cost-consequential decisions. If process selection is deferred until after detailed CAD is complete, the opportunity to optimize geometry, tolerances, and material for the chosen process is lost, and cost becomes unnecessarily high.
What are the five key criteria for selecting a manufacturing process?
The five key selection criteria are: (1) Production Volume—the annual or lifetime unit quantity, which determines economies of scale and tooling amortization; (2) Part Geometry—the complexity, internal voids, undercuts, and features that favor certain processes; (3) Material Requirements—strength, weight, thermal properties, and corrosion resistance; (4) Tolerance & Surface Finish—the precision and smoothness required; and (5) Cost Target—the maximum allowable manufacturing cost. All five must be evaluated together; process selection depends on the intersection of all five criteria, not on any single factor in isolation.
How do I choose between injection molding and die casting?
Injection molding and die casting serve similar markets but have different economics. Die casting is typically better for higher volumes (50k+ units/year) of aluminum or zinc parts with tight tolerances and complex internal features. Injection molding works across a wider volume range (5k to 1M+ units) and offers more material variety. Die casting has higher tooling costs but lower piece costs at high volume. For detailed comparison, see Die Casting vs Injection Molding.
At what production volume does each manufacturing process become economical?
Different processes have different volume breakpoints where tooling and setup costs are justified. Machining is economical from 1 to 10,000 units (no tooling cost required). Injection molding becomes competitive at 5,000-10,000 units depending on part size. Die casting requires 50,000+ units. Investment casting works from 500 to 100,000 units. Sand casting spans 1 to millions of units. Sheet metal stamping is economical at 50,000+. These ranges are approximate and depend on part complexity, material, and labor costs. Use process-specific cost models to evaluate your exact part.
How does part geometry affect process selection?
Part geometry is critical because different processes have different geometric capabilities and constraints. Injection molding handles complex shapes, thin walls, undercuts, and internal voids easily. Die casting is limited to relatively thick walls and external features. Machining can achieve tight tolerances but removes material, which is inefficient for near-net-shape parts. Forging is limited to relatively simple shapes but produces superior strength-to-weight. Investment casting achieves complex geometries with good surface finish. Evaluate your geometry against the capabilities of each candidate process before choosing.
What is the difference between die casting and investment casting?
Die casting uses high-pressure metal injection into steel dies. It is best for high-volume (50k+), aluminum or zinc parts with tight tolerances and complex internal features. Investment casting uses a lost-wax mold process. It is best for medium-volume (500-100k), complex parts requiring tight tolerances and excellent surface finish, or for materials not easily die-castable. Investment casting has higher tooling cost but superior surface finish and can handle higher-melting-point alloys. For detailed comparison, see Casting Process Comparison.
Can I use DFMA to compare manufacturing processes for my part?
Yes. DFMA contains process-specific cost models for 15+ manufacturing processes. You can estimate your part's cost in multiple processes and compare them side by side. DFMA shows cost breakdowns by component (material, process, tooling, secondary ops), accounts for volume-dependent economics, and lets you change specs to see how cost is affected. Use DFMA to identify the most cost-effective process for your part at your production volume. For a demo, see Schedule a Demo.
Find the right manufacturing process for your part
DFMA cost-estimates your part in 15+ manufacturing processes side by side. See cost breakdowns by component, understand why one process is cheaper, and identify design changes that could improve economics. With or without CAD.
