Custom Silicone Mold DFM Checklist: 10 Things to Check Before Ordering

Pre-Order DFM Checklist for Custom Silicone Molds

Are you planning to order a custom silicone mold? Stop. Before you pay for tooling, run this DFM (Design for Manufacturability) checklist. This guide is written for buyers, not just engineers. Let’s make sure your custom silicone molding order is right the first time.

1. Material Selection (LSR vs HCR)

Choosing the wrong silicone type is a costly mistake. Liquid Silicone Rubber (LSR) is great for high-volume, precision parts. High Consistency Rubber (HCR) works better for general industrial parts.

• Client mistake: "I just need silicone." No. Specify the hardness (Shore A), color, and grade (e.g., medical-grade LSR).
• Pro tip: If you need FDA- or ISO 13485-certified parts, say it now. Adding it later costs double.

2. Wall Thickness Uniformity

Silicone shrinks and traps air. Uneven walls cause sink marks and voids.

• Rule: Keep walls between 1.0mm and 3.0mm. Avoid sudden thickness changes.
• Real case: A client designed a medical part with one side 3mm and the other 8mm. The uneven shrinkage caused a sunken sealing surface. We scrapped 2,000 pieces before fixing the mold.

3. Draft Angles

Silicone sticks. Without draft angles, parts break during demolding.

• Rule: Minimum 1° to 3°. Deep cavities need more.
• Real case: A client designed a part with 0° draft for a "straight look." The part stuck so badly in the polished mold that we had to rework the tooling, adding 0.5° and delaying production by two weeks.

4. Undercuts & Sliders

Undercuts require sliding mechanisms in the mold. They increase cost drastically.

• Rule: Avoid 360° undercuts if possible.
• Real case: A client ordered a 360° undercut seal ring. We added 4 sliders. The mold cost jumped from $8,000 to $35,000. If you can change the design, do it before ordering.

5. Gate & Runner Design

The gate leaves a mark. Its position affects how the mold fills.

• Options: Cold runner, hot runner, or standard sprue.
• Check: Can you accept a gate witness mark? Where should it go? For multi-cavity molds, we must balance the runner system to ensure all cavities fill evenly.

6. Venting Requirements

Silicone is thick. Bad venting = trapped air = bubbles and short shots.

• Soluzione: Venting grooves or vacuum-assisted venting.
• Check: Tell us which surfaces are sealing faces or critical appearance areas. We cannot cut vents there.

7. Tolerances & Shrinkage

Silicone is not plastic. It shrinks.

• Data: LSR shrinks 2.5-3.5%; HCR shrinks 1.5-2.5%. Molds must be scaled up.
• Mistake: Clients often copy-paste plastic tolerances (±0.05mm) onto silicone drawings. It is impossible to hold consistently.

8. Surface Finish & Texture

A mirror finish looks great but increases sticking risks and tooling costs.

• Options: SPI polishing grades or texturing (matte).
• Check: Which faces need polishing? Which can be standard machined? release silicone more easily than mirror finishes. Learn more about silicone mold surface finish options.

9. Production Volume & Mold Material

Your order quantity decides the mold material.

• Aluminum molds: Best for prototypes/small batches (5,000 - 50,000 shots). Lower cost.
• Steel molds: Required for mass production (500,000+ shots). Higher initial cost, longer life.
• Check: Tell us your estimated annual volume upfront. We will help you reduce silicone mold cost by choosing the right material.

10. Insert Molding & Overmolding

Adding metal or plastic inserts complicates the mold.

• Risks: Inserts expand differently than silicone. They can shift during injection.
• Check: Do you need chemical bonding or mechanical interlocking? Overmolding requires precise shut-off areas.

Get Your Free DFM Review

Don't guess. Send us your 3D drawing (STEP/IGES). Jeff and our engineering team will review it and reply with DFM feedback within 24 hours. No charge. No obligation.

Upload Your Drawing for Free DFM Review

FAQ

Q: How long does a DFM review take before ordering a silicone mold? A: At Dibo Tech, we typically complete a full DFM review within 24 hours after receiving your 3D drawing and requirements.

Q: Can I order a silicone mold without a 3D drawing? A: If you don't have a 3D drawing, our modeling team can create it for you, though this service requires a separate quote and will add to the timeline.

Q: What tolerance can silicone molding achieve? A: Standard silicone molding typically achieves ISO 3302 Class M2 or M3 tolerances. Tight tolerances require special process controls and post-curing.

Q: How much does a custom silicone mold cost? A: Costs vary widely based on complexity, size, and material. Aluminum molds start lower, while multi-cavity steel molds with sliders cost significantly more. for an exact quote.

About the Author & Dibo Tech

My name is Kunfa Ye, but friends call me Jeff. I was born in 1986, the year of the Tiger. In 2011, my brother Autumn Ye and I co-founded Dibo Tech, rooting ourselves in the silicone rubber industry for fifteen years. Building from scratch, we navigated industry cycles and learned the true rewards of hard work. We have always built our business on technical expertise and integrity.

The silicone industry touches every corner of modern manufacturing. I deeply believe that behind every product lies trust, and the essence of business is mutual gain. Over these years, my proudest achievement is not personal financial independence, but helping our clients optimize supply chains and boost production efficiency. Their success is far more rewarding than personal milestones. Today, I aim to give back by sharing insights, answering engineering questions, and connecting people and resources.

Brand Name: Dibo Tech

Slogan: Dibo Technology Silicone Manufacturing Specialists

Website: https://samxine.com/

Our Mission: Based on strong technical capabilities and quality first, we are committed to innovative and eco-friendly silicone rubber production, providing reliable silicone solutions while fulfilling social responsibilities for a sustainable future.