The Power of Good Teamwork & Collaboration
Recently I had a customer who had an issue with some products they were receiving having a warping issue with a rubber product.
It can be very frustrating as a customer to order a product and have issues with it further down the line. Intuitively, it’s easiest to blame the manufacturer for the issue. You hand a supplier your files, they say they can make it, so everything should be fine after that right? Well after we vet a manufacturer that’s normally how it goes. However, there are some rarer instances in which that’s not always the case.
It’s not always the fault of the manufacturer that the finished product ends up less than satisfactory, especially when the product requires complex manufacturing processes.
In this case, our customer’s project required injection molding. Put simply, with injection molding, very hot material is injected into a mold, cooled, and ejected off the mold. There are several things that can cause a scrap part with either a design or the manufacturer.
Potential Manufacturing-Related Issues with Injection Molding
- Improper mold temperatures: Incorrect temperature settings can cause warping or sticking. If the material isn’t hot enough it may end up not filling the mold properly. If it isn’t allowed to cool for the proper amount of time it may warp when it gets ejected from the mold.
- Inadequate use of release agents: Release agents are chemical materials used on the surface of the mold or mixed in with the mold resin itself. These agents are used to help the part of the mold be ejected seamlessly off it. Sometimes manufacturers will not use enough. Skimping on release agents or applying them unevenly can lead to adhesion issues.
- Worn-out molds: Molds will degrade over extended usage. Lack of regular maintenance can degrade mold performance. These molds can often be reworked to improve the quality of the parts injected.
Potential Design-Related Issues
Sometimes it isn’t the fault of the manufacturer but of the design that parts get scrapped. Anything can be designed, but not everything can be manufactured with current technology limitations.
Here are some features that are often very difficult or not possible to have injection molded.
Parts with no draft angles: Without proper draft angles, parts can get stuck in the mold. A draft angle is a slight taper on a vertical wall or side of a part meant to allow parts to be ejected from the mold. Proper draft angles allow for improved surface finishes, reduce scrap rates, and extend the life of the mold by reducing the amount of force needed for part ejection.
Complex angles and undercuts: Designs with undercuts or sharp angles can complicate demolding. This is because molten plastic is viscous, and as it gets injected into the mold, it has a hard time filling corners or other sharp angles.
Think of the difference between Jello and water filling a container, there are going to be gaps with Jello especially on the corners. This is why rounded corners and angles are often preferred with injection molds.
Thin walls and features: These can deform during demolding, leading to defective parts. As rubber and plastic cools, there is often shrinkage. It can be difficult to ensure a part with a thin feature will be made properly without breaking.
Material-Related Issues
Some materials naturally have higher adhesion properties, making demolding more challenging without proper adjustments. Stickier materials will have a harder time getting ejected from a mold without harming the quality of the part.
In our client’s case they had a thin wall that was also a critical wall, that if it didn’t cool perfectly warped the shape of the product. While the manufacturer was able to make the product, the scrap rate was extremely high because of it, making the part too costly to produce without having to change the designs; in this case, correct a thin wall and draft angle.
With product sourcing, and especially with taking a new product to market, a collaborative mindset will go a long way to addressing issues quickly and seamlessly.
Tips to help navigate potential problems
Design for Manufacturing, or DFM, is a design principle where products are designed with current manufacturing capabilities in mind. It is meant to make a design that fits around the limitations of technology. This mindset helps save money in the long run and will expedite the manufacturing process by reducing delays in troubleshooting designs.
The engineer you have designed your product should have experience or deep industry knowledge in similar parts. There are thousands of product designers to choose from, but fewer with expert design for manufacturing mindsets.
Be patient with first time orders – Manufacturers have to make tooling and come up with processes for a first time order. They also have to program their machines to make the parts correctly.
Choose the right team – At Global Trade we take care to make sure our customers have the most seamless process in getting their products made efficiently and cost effectively. We will review your drawings to minimize the chances of production delays occurring and will walk you through the sourcing process.
Get the process started today, contact us!