PPS Plastic Injection Aerospace/Military Case Study

Pre-Assembly Cracking in Aerospace/Military Part Solved

Customers rely on master molders at Plastic Molded Concepts to solve complex plastic molding issues.

This customer had a recurring PPS plastic injection molding issue that their current supplier could not solve: pre-assembly part cracking.


A global company specializing in technological development for security, military and aerospace industries contacted us about an issue they believed was being caused by their molding supplier.

The customer explained to us that the problem was in pre-assembly part cracking. When the parts were ready for assembly they were already showing a multitude of cracks. This prevented the parts from being used in production.

The company was forced to impose a mandatory line shutdown until they could identify why the cracks were occurring and resolve the disruption issue. We knew the company’s costly production downtime necessitated a fast resolution.

After asking a series of troubleshooting questions, the company realized they weren’t able to provide the answers we needed because they didn’t have enough technical information about their supplier’s PPS plastic injection process and tooling. The company asked if we would help them resolve this issue.

What Went Wrong: Incorrect Molding Technique

We began an in-depth investigation to determine where the source of the cracks were originating. We quickly identified that the supplier was violating proper process techniques for the specified material, 50% glass-filled PPS (polyphelene sulfide).

The supplier was a commodity molder who specialized in high volume molding that used commodity resins, not engineering-grade resins. They did not have the experience or capabilities necessary to deal with an engineering-grade resin. This lack of process-specific knowledge resulted in the supplier manufacturing the tooling with a shrink rate suited for a cool mold when a hot mold was required.

This stress level molded into the part was causing the product to crack before it even hit post-molding machining to finish the part to its final tolerance requirements.

Our Findings

We provided a detailed analysis of our findings to the company, explaining how the supplier’s molding technique was responsible for half the parts being damaged or defective. We also explained that commodity molders, most often, do not specialize in the processing of engineering-grade resins, nor do they have the necessary equipment to handle it.

After discussing our findings and recommendations with the company, they decided to part ways with their supplier and immediately move the molding production to us.

The Solution

The solution necessitated a new mold with special shrink features that allowed the parts to establish their targeted dimensions, while finished machining brought the parts to final dimensions.

The newly implemented process and solution eradicated the mold cracking completely, resulting in strong, undamaged parts that are able to be assembled in a full quality state.

The Follow-Up

Since this project, the company has brought us over a dozen more projects, as well as consulted us on research and development for new products.

Why Customers Choose Plastic Molding Concepts

Today, 90% of the world’s molding industry is commodity-based. This means there are very few molders who have the capabilities, knowledge or machinery to process parts using the engineering-grade resins required for technical and complex molding projects.

Many companies come to us because their previous supplier didn’t understand or wasn’t capable of properly processing engineering-grade resins nor were the mold designs capable of minimizing the stress levels of the molding process.

Our master molders only work with engineering-grade resins, which means we’re one of very few companies in the world today who have the expertise and equipment to handle complex molding projects that the commodity molders choose to avoid.

Every day, we help make companies risk-adverse through our knowledge and capabilities, which is why our customers stay with Plastic Molding Concepts. Request a quote today!

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