Often, customers bring us the drawings and confidently say, "This product is very simple. Just follow the instructions."
After our engineers review the drawings, they usually find some issues - not that they can't be made, but that the resulting product has poor quality, high costs, and a low yield rate.
If these problems are identified during the design stage, they can be fixed with just a small adjustment; but if they are addressed after the molds have been made and the product has been produced, the cost will be much higher.
Today, we will discuss the 5 most common pitfalls in the design of silicone products. If you are developing silicone products, reading this will help you save a lot of money.
The first pit: Excessive wall thickness
What is the manifestation?
When drawing the product design, the customer habitually depicts the product as being "robust" - with a wall thickness of 3mm, 5mm, or even thicker. They believe that a thicker wall makes the product more durable and has a better texture.
Why is this a pitfall?
Silicone and plastic are different. Plastic can have a thick wall, but for silicone, the thicker the wall, the more problems arise:
Difficult mold processing: The thick silicone wall is difficult to mold evenly, and it is prone to wear.
Easy bubble formation: The thick product is more likely to trap air bubbles, resulting in a surface bulge or internal voids.
High cost: More material is used, and the curing time is longer, so the unit price is naturally higher.
Poor feel: The overly thick silicone feels heavy and loses the softness and skin-friendly nature of silicone products.
How to fix it?
The recommended wall thickness for silicone products is between 1-3mm. If a thicker wall is truly necessary, consider a hollow structure or reinforcement design to achieve strength through the structure rather than by adding more material.
The second pit: Too many sharp corners
What is the manifestation?
There are many right angles, sharp edges, and pointed corners in the product design. It looks sharp and has a strong design sense.
Why is this a pitfall?
Silicone is an elastic material, not a hard material. The design of sharp corners brings several problems:
Difficult mold processing: The sharp corners are difficult to process precisely, and they are prone to wear.
The product is prone to tearing: The stress concentration at the sharp corners causes the silicone to crack from the sharp corners when under force.
Difficult demolding: The sharp corners are prone to getting stuck in the mold, and the demolding process causes damage to the product.
The feel is poor: The sharp corners feel stiff and do not match the "soft and skin-friendly" positioning of silicone products.
How to fix it?
Wherever possible, round the corners. The recommended radius for silicone product corners is not less than 0.5mm, and the critical stress areas should be 1mm or more. The rounded corners are not only easier to make but also have a better feel and a longer product lifespan.
The third pit: Excessive tolerance requirements
What is the manifestation?
The drawings are densely marked with tolerances, often ±0.05mm or ±0.1mm.
Why is this a pitfall?
Silicone has a natural property - shrinkage. Silicone shrinks by 1%-3% from high-temperature molding to room temperature cooling. This means:
Silicone products are difficult to achieve the precision of metals or plastics.
The tighter the tolerance requirements, the higher the mold requirements, the lower the yield rate, and the higher the cost.
Some tolerances are physically impossible to achieve, not due to factory capacity issues.
How to fix it?
Distinguish between critical dimensions and non-critical dimensions.
Critical dimensions (affecting assembly and function): ±0.1-0.2mm can be achieved.
General dimensions: ±0.3-0.5mm is normal.
Non-critical dimensions: No tolerance is marked, and it is controlled according to normal procedures.
If you are unsure which dimensions should be tight and which should be loose, tell the engineer about the product's purpose and let them help you determine.
The fourth pit: No consideration for demolding
What is the manifestation?
The product design has many inverted structures, deep cavities, and narrow grooves. It looks powerful in function, but the mold simply cannot be removed.
Why is this a pitfall?
Although silicone is soft, it can be forcibly demolded, but the cost of forced demolding is:
The product is damaged, deformed
The mold life is shortened
Production efficiency is low, and the cost is high
The yield rate decreases
How to fix it?
When designing, consider the demolding direction:
Try to avoid inverted structures
For deep-cavity products, leave a demolding slope
The width of the narrow groove should be sufficient to facilitate the removal of the silicone
If the structure really requires an inverted design, communicate with the engineer to see if a special mold structure can be used to solve the problem
The fifth pit: Ignoring post-processing requirements
What is the manifestation?
The customer only considered the product itself and didn't take into account whether additional processes such as printing, laser engraving, spraying, or adhesive backing would be required later.
Why is this a problem?
Post-processing has an impact on product design:
Laser engraving: A flat area for engraving needs to be reserved. Poor engraving results on curved or complex shapes.
Screen printing: A printing area needs to be reserved. Rough surfaces cannot be printed clearly.
Spraying: There should not be too deep dead corners on the product, otherwise it cannot be sprayed.
Adhesive backing: A flat backing area needs to be reserved. Small or narrow areas cannot be adhered firmly.
Assembly: If the product needs to be assembled with metal or plastic, the assembly gap should be reserved in advance.
How to change?
Think clearly during the design stage: After this product is made, will additional processing be required?
If there is a need for post-processing, inform the engineer in advance and have them reserve the position and space for post-processing in the drawing stage for you.
Advice for customers:
The design of silicone products is very different from that of metals and plastics. Using the thinking for metals to design silicone products is very likely to cause problems.
The easiest way: Before drawing the blueprint, have a chat with the factory engineer first.
Clearly explain your product's purpose, usage scenarios, and functional requirements to the engineer, and ask for some design suggestions from them. Spending half an hour communicating might save thousands of dollars in mold modification fees.
At Hongxianda, after receiving the customer's blueprint, we will conduct a manufacturability review and point out the problems in the design in advance, and work with the customer to optimize it. This process is free, but it can help the customer avoid many pitfalls.
If you are designing a silicone product and are unsure if the blueprint can be made, welcome to have a chat with Hongxianda. Send your blueprint to us, and we will help you check it.