Identifying a world-class quality assurance test solution

The challenge

Merlin Polyurethanes, a polyurethane molding manufacturer, and Enertor, a manufacturer of bespoke orthotics, have been working together since 2018 to jointly develop a new generation of insoles for the mass sport and recreation market.

As part of this partnership, in which Enertor provided the concept and Merlin provided the manufacturing facilities, two new types of insoles were developed and launched, receiving positive customer reviews from consumer publications and websites. However, when production began ramping up to meet increasing demand, it became apparent that the hardness of the products measured at Merlin and at Enertor was inconsistent. Testing results varied significantly between the two companies as well as between individual operators, indicating potential issues with either the manufacturing process, the testing process, the testing equipment, or all three.

This culminated in Enertor rejecting several batches of the new insoles due to their substandard quality, affecting the partnerships ability to rapidly scale up production, casting doubt on the feasibility of the venture and resulting in substantial product waste and lost revenue.

It became apparent to both companies that the standard method of assessing industry hardness using off-the-shelf durometers was not suitable for these new products. To control the manufacturing process and provide Enertor with consistent quality, a more suitable hardness testing method was required.

Merlin Polyurethanes decided to apply to Innovate UK for access to expertise and equipment at NPL through the A4I programme.

The solution

NPL conducted a thorough evaluation of the equipment used to test Enertor’s insoles, taking precise measurements at every stage of the process. It looked carefully at the multitude of variables that could have impacted the accuracy and effectiveness of the test. NPL’s highly controlled environment, and its advanced equipment, allowed the team to remove any relevant variables and find the best quality assurance test solution.

The team utilised Instron systems for their measurements, these systems are specifically designed for highly accurate materials testing. In this case, the Instron systems were used to create a compressive load displacement test to show how much the insoles changed shape when pressed with a certain force. This was done with an accuracy that Merlin had previously not been able to deliver.

Following the research and recommendation of the NPL scientists, Merlin Polyurethanes designed and built three bespoke hardness measuring devices specifically for the new Enertor products, accounting for their unique softness, lightweight density, and slim design. The three devices were benchmarked against each other, and their accuracy and consistency were validated by both companies. The accuracy of the applied hardness measurement went from an initial spread of +/-10 units to +/- 1 unit and the new testing method proved to be consistent, repeatable and reliable.

“After being deeply concerned by the inaccuracy of the standard industry hardness measuring tests we had used, I was quickly amazed by the improvement we achieved thanks to this project with NPL,” explains Steve Hurst, Owner and Managing Director at Merlin Polyurethanes.

The impact

The project delivered a wide variety of positive effects on Merlin Polyurethanes and its client, Enertor. Merlin Polyurethanes gained the confidence to restart production and Enertor to resume its orders. Manufacturing capacity was swiftly scaled up to fulfill the growing demand. Investment in further machinery and equipment to increase output became financially justified and production waste was dramatically reduced from approximately 20% to less than 2%.

 

Production capacity went from 20,000 units in 2020 to over 100,000 within two months of completing the A4I project. The growing orders from Enertor became a significant percentage of Merlin’s turnover, making the company more diverse and less dependent on the previous markets that made up its historical client base. The change in results was significant enough for Merlin Polyurethanes to regain Enertor’s trust, quickly leading to both companies signing a 5-year contract for exclusive cooperation.

“I cannot thank Innovate UK and NPL enough for their work, which has made a tremendous difference to Merlin’s turnover and business continuity” says Hurst.