In this interview, we learn about Gleason Plastic Gears (GPG), a division of Gleason Corporation that specializes in designing and manufacturing plastic gears using their proprietary no-weldline technology. GPG has diversified its customer base and serves various industries such as automotive, medical, electronics, home and leisure, marine, education, and hobby. The interview covers topics such as the advantages of the no-weldline technology, surprising applications where plastic gears are replacing metal gears, promising materials and methods for the future of plastic gears, challenges faced by plastic gear designers, and recent developments in services, software, and manufacturing technology. The interview concludes with an overview of GPG’s plans for the future, including the potential utilization of a Gleason P60 Gear Hobbing Machine for precision hobbing of polymer gears and their focus on biomaterials for environmental reasons.

Gleason Plastic Gears as such was established in 2015. What markets have been the focus of the division and how have the division and its markets evolved? 

GPG continues to diversify its customer base and expand into different markets. Automotive and medical have always been key customers, but GPG also provides services to industries such as electronics, home and leisure, marine, education, hobby, etc. It’s not just the molding work either—there are plenty of customers looking for gear and system engineering as well as gear inspection services. Being part of Gleason Corporation, and having KISSsoft AG in Switzerland as well as Gleason Metrology Systems as sister companies, makes GPG excel in design and engineering as well as gear inspection services and differentiates us well in the plastic gear’s market.

Is the proprietary no-weldline technology still at the heart of GPG? What distinguishes this from other processes?

The no-weldline technology benefits customers in many ways. From a quality standpoint, it allows the gears to be very round and measured at a very high gear quality because the shrinkage is isotropic and close to the material data sheet. From a performance standpoint, we do not have to worry about the integrity of the material strength being compromised at the weldlines, nor residual stresses molded into the gears. From an overall process standpoint, we very rarely have to correct the gear geometry in the tools to account for weldlines. This translates to fewer tooling groom iterations; reduced costs for customers; and fewer headaches from non-round gears that require compensation in the tooling. Overall, we are usually able to hit the tolerances and dimensions for the gears the first time. It is not uncommon to achieve between an ISO A6 to A10 or AGMA Q7 to Q11, depending on the customer’s needs.

What are some surprising applications where plastic gears are replacing metal gears?

High-temperature actuators, E-bike transmissions, low-orbit satellites, etc. Plastic gears are capable of being in so many different applications, but only if designed and molded correctly. In order to replace metal gears in some of these challenging applications, proper gear design techniques must be used. KISSsoft is a Gleason Company and is the gear design software that GPG has relied upon for plastic gear design and optimization since 2011. What’s even better is that GPG has access to every available KISSsoft module which allows us to take advantage of all possibilities to design a plastic gear.

What are some of the most promising materials and methods of manufacturing for the future of plastic gears?

GPG is not limited to specific materials. We have used everything from unfilled POM up to carbon-filled PEEK. There are also some thermoset materials that are being explored which present their own set of processing challenges. In addition, GPG is actively looking into using biomaterials in order to meet specific environmental goals for Gleason and our customers.

With injection molded plastic gears, the designer has significant freedom in defining the tooth form because it is not the result of a generating process. However, the influence of the injection molding process on the final tooth geometry plays a determining role in plastic materials with high shrinkage. What are the challenges plastic gear designers face that are distinct from working with other materials and processes?

The same challenges any molder faces! Certainly, predicting the shrinkage is not an exact science. Once again, this comes down to utilizing the no-weldline technology to predict shrinkage more accurately, if and when possible. When there’s uncertainty, we stay steel-safe in the tool and may utilize flow simulation software. Often these tools are not needed for our gears, but for non-gear molding and assembly work it offers additional value to our customers’ projects that contain other components. For instance, we may mold the housings as well, which is important to us because of how critical center distance control is for fine pitch gearing. You can produce a great gear design and molded gears, but if the nominal center distance and tolerances are not controlled, there could be many other problems to deal with.

What is on the horizon for GPG? What recent developments have been introduced in services, software, and manufacturing technology? 

Typically, customers will come to us for engineering services, which we provide first, and when they purchase a production mold from us, we credit back a portion or all of the engineering costs towards the cost of the mold.

GPG continues to leverage Gleason and KISSsoft technologies to provide additional value to customers. GPG molds VDI test gears for different gear testing companies, universities, and chemical companies contributing to gathering appropriate gear material endurance limits at a range of temperatures. This data is often provided to KISSsoft and entered into the database, making the life of a plastic gear designer a lot easier. Gleason also has plenty of its own internal test data based on years of experience and test data feedback from customers. As mentioned previously, GPG continues to look at biomaterials for environmental reasons. From a prototyping standpoint, we consider acquiring our own Gleason P60 Gear Hobbing Machine for precision hobbing of polymer gears, for prototype inspection, we use wire EDM “master” gears, analytical inspection, and even laser inspection on a Gleason GMSL machine. Finally, we have developed a niche for designing and molding half-enveloped worm wheels, bevels, and face gears, which many others would not be comfortable offering. We excel with challenging applications, materials, and types of gears.