Injection Molding DFM Analysis
Send a STEP file and get an actionable design review within 24 hours: wall thickness, draft, gate position, weld lines, shrinkage and warp risk, each with a specific change and its effect on tooling cost. Free, with no obligation to place a mold order.
Free Consultation24h
DFM Turnaround
100 pcs
Molding MOQ
±0.05mm
Part Tolerance
Free
Review Cost
Materials
| Grade | Properties | Typical Applications |
|---|---|---|
| ABS | Shrinkage 0.4 to 0.7 percent, easy flow, good impact strength, plates well and bonds with adhesives, prone to sink marks on thick ribs | Consumer electronics housings, appliance covers, toys, tool cases, cosmetic enclosures |
| PC (Polycarbonate) | Shrinkage 0.5 to 0.7 percent, high impact strength and clarity, needs higher melt temperature and thorough drying, stress cracking risk at molded-in bosses | Transparent covers, safety guards, lenses, electrical housings, medical device shells |
| PP (Polypropylene) | Shrinkage 1.0 to 2.5 percent, chemical resistance, living hinge capability, high shrinkage makes tolerance control harder than ABS | Containers, caps, living hinges, automotive interior parts, packaging |
| PA66 (Nylon) | Shrinkage 1.0 to 2.0 percent, good strength and wear resistance, moisture sensitive, glass filled grades shrink less but wear the mold faster | Gears, brackets, housings, structural parts, under-hood components |
| ABS/PC Blend | Shrinkage 0.5 to 0.7 percent, better heat resistance than ABS with better flow than PC, useful where both properties are needed | Automotive interior trim, electronics housings, power tool bodies |
| POM (Acetal) | Shrinkage 1.8 to 2.5 percent, low friction and high fatigue resistance, poor adhesion for painting, strong chemical resistance | Gears, bearings, sliding parts, clips, precision mechanisms |
| TPE / TPU | Shrinkage 1.0 to 2.5 percent, flexible with shore hardness from 40A to 70D, bonds to rigid substrates in overmolding when the chemistry matches | Soft grips, seals, cable strain reliefs, wearable bands, overmolded handles |
Process Parameters
| Parameter | Standard Range |
|---|---|
| DFM Report Turnaround | within 24 hours of CAD upload |
| Wall Thickness Review Band | 1.0 - 3.5 mm by resin |
| Draft Angle Review | 0.5 - 2° per surface, more on texture |
| Nominal Part Tolerance | ±0.05 mm, tighter by agreement |
| Gate Options Reviewed | Edge, pin point, submarine, hot runner, valve gate |
| Shrinkage Allowance | 0.4 - 2.5 percent by resin and fill direction |
| Warp Analysis | Differential cooling and fiber orientation effects |
| Mold Flow Simulation | Available on request for critical parts |
| Cavity Count Reviewed | 1 to 16, balanced against volume |
| Texture and Draft Interaction | VDI 3400 grades, added draft per 0.025 mm depth |
| Molding Machine Range | 50 - 800 T |
| Maximum Molded Part Size | up to 800 x 600 x 400 mm |
Surface Finishes
Texture (VDI 3400)
Mold surfaces etched to a VDI grade from 12 to 45, transferring a matte or leather pattern to the part and hiding flow marks and minor sink. Each 0.025 mm of texture depth needs about 1 degree of extra draft, which the DFM report accounts for before the steel is etched.
SPI Polish (A-1 to D-3)
Mold steel polished to an SPI grade from mirror A-1 to matte D-3, with the finish copied onto every part. Gloss finishes show sink and flow lines most clearly, so a high polish raises the design standard for wall uniformity rather than lowering it.
Painting and Soft Touch Coating
Sprayed colour, UV clear coat or soft touch lacquer on molded parts, applied after masking. It covers minor cosmetic defects but adds cost per part, so a texture that hides marks is often the cheaper route at volume.
Laser and Pad Printing
Permanent logos, scales and part numbers applied after molding, with laser marking giving better wear resistance than pad printing on most resins.
EDM Finish
Non-directional spark eroded texture on cavity surfaces, useful on deep ribs and small features where polishing cannot reach, and it diffuses light evenly on matte parts.
Assembly and Ultrasonic Welding
Snap fits, screws, ultrasonic welding and heat staking designed in at the DFM stage so the part arrives ready to assemble rather than needing a second design round.
Design for Manufacturing (DFM)
- Keep nominal wall uniform within 10 percent; a local thick section causes sink on the visible face and voids inside
- Core out thick bosses to a wall of 60 percent of nominal, since a solid boss shrinks away from the surface and pulls a dimple
- Add 1 degree of draft per 0.025 mm of texture depth on top of the base 0.5 to 2 degrees
- Place gates where weld lines land on a hidden or low-stress area rather than across a visible face
- Check rib thickness at 50 to 60 percent of nominal wall to avoid sink on the opposite surface
- Design snap fits with a strain below 60 percent of the resin yield strain for the assembly cycle
- Keep flow length to wall thickness ratio under roughly 150:1 for ABS and 100:1 for glass filled grades
- Allow for anisotropic shrinkage on glass filled resins, where flow direction shrinks less than cross flow
- Put cosmetic surfaces on the cavity side, since ejector marks appear on the core side
- Upload STEP, IGES or native CAD files and receive a report listing each issue, the fix and the tooling cost impact
Tooling & Capacity
| Type | Lead Time | Suitable For |
|---|---|---|
| Soft Tooling (Aluminum) | 2 - 3 weeks | 25 to 1,000 pcs, design validation before steel tooling |
| Production Mold (P20 / H13) | 4 - 6 weeks | 1,000 to 1,000,000 pcs, stable annual volume |
| Multi-Cavity Mold | 5 - 6 weeks | High volume runs where cycle time dominates cost |
| Hot Runner or Valve Gate System | 5 - 7 weeks | Thin walls, engineering resins, zero-sprue requirements |
Quality Assurance
- DFM report reviewed by the tooling engineer who will cut the steel, not a sales template
- Dimensional and cosmetic requirements captured before gate and ejector layout
- Resin grade and shrinkage data confirmed against the supplier datasheet
- Mold flow simulation run on critical parts when fill or warp risk is high
- T1 trial samples measured and compared against the DFM assumptions
- CMM inspection on first article and periodic samples during production
- In-process monitoring of shot weight and cavity pressure on tight features
- Resin lot traceability kept from incoming material to shipped parts
- Third-party inspection by SGS, Bureau Veritas or TUV arranged on request
- Dimensional report and Certificate of Origin shipped with every lot
Applications
- New product design validation before tooling capex
- Cost down review of an existing molded part
- Tooling feasibility check on a tight-tolerance part
- Supplier comparison and second-source evaluation
- Design for assembly review of a multi-part housing
- Warp and sink troubleshooting on a part already in production
- Material substitution review, for example ABS to ABS/PC
- Overmolding and insert molding feasibility
- Thin wall feasibility on battery and handheld enclosures
Why Choose FHY Precision
The review is written by the engineer who will build the mold, so it reflects what actually gets cut
Delivered within 24 hours of CAD upload, which keeps a design cycle from stalling for a week
Each issue comes with the specific change and its effect on tooling cost, not a generic checklist
Free of charge and with no obligation to place a mold order
Resin-specific data used for shrinkage and draft advice rather than one rule for every plastic
Mold flow simulation available when the part geometry warrants it
Documented quality system with third-party inspection arranged on request
Factory-direct in China with in-house tooling and molding, so the advice and the execution stay with one team
FAQ
1. What is DFM analysis in injection molding?
Design for Manufacturing is a review of a plastic part against the constraints of the molding process before the mold is cut. It checks wall thickness, draft angle, gate position, rib and boss proportions, weld line placement, shrinkage allowance and ejection, then lists what to change. The point is to fix on screen what would otherwise cost weeks and steel to fix in the tool.
2. Is the DFM report really free?
Yes, the first review is free and carries no obligation to order a mold. We treat it as the technical conversation that comes before a quotation. If the part needs iterative review across several design revisions, the first two rounds stay free and further rounds are quoted, which is stated upfront rather than billed after the fact.
3. How fast will we receive the analysis?
Within 24 hours of receiving a usable CAD file on a working day. Simple parts often come back the same day. Parts needing mold flow simulation take 2 to 4 days, because the simulation includes meshing, fill analysis and a warp prediction. The report states which route your part took so the timeline is never unclear.
4. What files do you need for a DFM review?
A STEP or IGES file is enough to start. Native CAD files in SolidWorks, Creo, NX or Inventor let us work faster and check the feature tree. A 2D drawing adds tolerance and finish intent, and a short note on the part function, resin choice and expected volume lets the review prioritize issues that matter for your volume instead of listing every theoretical risk.
5. What does the report actually contain?
It lists each issue found with a screenshot of the location, the reason it matters, the recommended change and, where relevant, the effect on tooling cost or cycle time. Wall thickness findings include a thickness map. Draft findings are marked per face. Gate and weld line findings show the proposed gate position. The report ends with a summary of what must change before tooling and what is optional.
6. What wall thickness should a plastic part have?
Nominal wall depends on resin and part size: roughly 1.2 to 2.5 mm for ABS and ABS/PC, 1.5 to 3.0 mm for PC, 1.0 to 2.5 mm for PP, and 1.5 to 3.5 mm for glass filled PA66. The more important rule is uniformity within about 10 percent, because a localized thick section cools last and pulls a sink mark on the opposite face.
7. How much draft angle does my part need?
A base of 0.5 to 1 degree per side on vertical walls, 1 to 2 degrees on deep ribs and bosses, and an extra 1 degree for every 0.025 mm of texture depth. Textured surfaces need more draft than polished ones because the pattern grips the part. Insufficient draft shows up as drag marks, white stress lines and ejection cracking, all of which the review flags by face.
8. Do you account for material shrinkage?
Yes, and it is resin specific. ABS shrinks 0.4 to 0.7 percent, PC 0.5 to 0.7, PP 1.0 to 2.5, and glass filled PA66 about 0.3 to 0.6 in the flow direction but more across flow. The cavity is cut oversize by the shrinkage allowance, and for anisotropic resins the allowance differs by direction, which is why material choice is confirmed before steel is cut.
9. Where should the gate be located?
The gate goes where it fills the cavity evenly, keeps weld lines off visible and high-stress areas, and allows the sprue to be removed without marking a cosmetic surface. Options include edge, pin point, submarine, hot runner and valve gate. The review proposes a position with the fill pattern shown, because gate choice affects both appearance and the tooling cost.
10. What is a weld line and why does it matter?
A weld line forms where two flow fronts meet and fuse imperfectly, leaving a visible line and a locally weaker section. It matters on structural parts and on any painted or high gloss surface. The review moves gates so weld lines land on hidden faces or outside load paths, and where a weld line must exist, it notes the strength reduction so the design margin accounts for it.
11. Can you predict warpage before the mold is cut?
Differential cooling, uneven wall sections and fiber orientation all cause warp, and all three are assessable. Wall thickness and rib layout are checked in the standard review, and mold flow simulation predicts warp magnitude for critical parts. When a flatness callout is tighter than about 0.1 mm on a large part, we recommend simulation before committing to steel.
12. How is DFM different from mold flow analysis?
DFM is rule-based review of geometry against process constraints and takes hours. Mold flow simulation solves the fill, packing and cooling numerically and predicts pressure, temperature, weld line position and warp, taking 2 to 4 days. DFM catches most problems cheaply; simulation is used where the geometry or tolerance is demanding enough that a numerical prediction is worth the extra time.
13. Will you sign an NDA before reviewing our design?
Yes, we sign a mutual NDA before receiving files when a customer asks. Many customers send a simplified model first to start the conversation, then release full detail once an NDA is in place. Design files are not shared outside the tooling team, and they are not used for any other customer project.
14. Does a free DFM review commit us to ordering a mold?
No. The review is independent of any order and we do not withhold the findings if you later build the mold elsewhere. Customers use it to compare suppliers on technical grounds, which is a reasonable way to choose. If you do proceed with us, the review becomes the basis of the tooling specification, so nothing is reviewed twice.
15. Can you review a part that is already in production?
Yes, and this is a common request when a part warps, sinks or fails at assembly. Send the model, the current gate position and photos of the defect, and the review will identify the likely cause and the cheapest correction, which may be a die insert change rather than a new tool. We also review parts quoted elsewhere to check whether the price difference hides a tooling compromise.
16. What quantities do you mold after the review?
MOQ is 100 pieces for production molding, and soft aluminum tooling can start at 25 pieces for validation. The DFM report notes where the design suits a soft tool and where it needs hardened steel, since a part with fine texture or tight tolerance may not release cleanly from aluminum. Cavity count is recommended against your annual volume, not against the first order.