There are many ways to be a sustainable company. In Part 3 of our in-depth look at the daily operations of the injection molding business of Xten Industries, our focus is on green design for more efficient manufacturing.
Xten Industries works hard at keeping its eye focused on productivity, profitability, efficiency, sustainability, and solving customers’ challenges with creative solutions. Opportunities for all of these exist in the various stages of the mold/molded part design, material selection, and the molding process chosen.
Mark Dirr, director of engineering for Xten, says that inmold operations offer both customers and Xten ways to reduce scrap, enhance productivity, and reduce costs-to-manufacture. The company provides inmold labeling and decorating, as well as other creative molding processes.
“The collaboration effort gave me a better understanding of the original design intent, and allowed me to ask questions of the OEM and the vendors so we could brainstorm problems before those problems occurred,” says Dirr. “It also brought the spirit of all the companies working together at the front of the program, which was key to meeting the compressed time schedule—time-to-market was key.”
One result of this collaborative effort was the elimination of a number of components by incorporating their features into a single molded part. Another was to eliminate secondary assembly operations and perform inmold labeling.
“We were able to eliminate a large backing plate, incorporate snapfit components, and add an inmold label rather than place a pressure-sensitive label onto a metal piece after the molding, then screwing that plate on,” explains Dirr. “We eliminated a significant amount of metal, eliminated a screwing operation, and gave the customer the decoration they were looking for. Ultimately, we gave the customer a much more simplified, compact version of what they were originally looking for.”
Wall thickness matters
The biggest impact from a cost-saving and sustainability standpoint is wall thickness. “Less wall thickness means less material, which translates into less machine time,” states Dirr. “Cycle time is directly associated with machine time.”
While that might seem logical to most people, Dirr adds that material thickness is one area people tend to miss, and thus don’t design for optimum material usage. “For example, a part designer will make very thick bosses for adding inserts, but that just adds more cycle time, and can cause quality problems such as sink marks and stresses in the part.”
Educating customers is key when designing parts and molds. “Sometimes we have to fight the customer’s engineers to get them to reduce the thicknesses, so we’re working with engineers directly, trying to get them to understand why thinner walls work. You don’t have to overdesign a part, which they typically do. Also, we’re running finite element analyses [FEA] to help us do a better job of defining what the customers’ design needs are from a structural standpoint.”
Wall sections that are too thin are a problem too, however. That is why it’s critical that Xten understand the customer’s design intent. “The more I understand the product and what the customer needs it to do, the better I can design the mold for manufacturability,” Dirr says.
Engineering creativity means efficiency, sustainability, profitability
Kelly Mills, project engineer for Xten, comments that inmold labeling and decorating have provided good opportunities for Xten to shine with customers. “We had an application in which we were able to work with our label supplier to get a label that goes around a medical container that has to be reused 500 times,” Mills explains. “We see many containers going in this sustainable direction, converting one-time-use containers into durable goods.”
While many OEM customers are becoming savvier about molds and molding processes, there’s still some educating needed in the relationship. Mills says that interaction and conversation are critical so that both parties understand what the customer needs and how best to meet those needs from Xten’s viewpoint.
“It works both ways,” notes Mills. “Sometimes the customer asks us for our input—‘How can we do this or that? Can we core out a wall? Use less material? Reduce cycle time?’ It’s a two-way street. Sometimes we come up with a new solution and talk to them about it.”
For a lid application, an Xten customer approached the molder with 10 styles of lids, and wanted to design a product that would produce minimal scrap, maximize efficiencies, and reduce overall costs. “We designed molds with interchangeable inserts to mold the various-sized lids, optimized the amount of space allotted to us in the mold, and made them neatly stackable to conserve on space in shipping. All of these things were incorporated at the design engineering level,” says Mills.
Many OEMs don’t have in-house expertise with inmold design and molding, so they look for suppliers with this engineering experience. Getting their molded parts supplier involved early in the design process overcomes this deficiency. For Xten, says Mills, “It helps us utilize our time better, and more efficiently use our resources to accomplish what we need to do in a timely manner.”
Often the main goal in processing is to optimize cycle time in very high-volume products. Mills adds that in some cases, optimizing a part design can result in an 18%-19% cycle time reduction. For one project, Mills looked hard at the tool design, focusing on thermal transfer of the materials in the tooling, and using conformal cooling. Another project made use of a set of pilot molds to test out the process. Then it was just a matter of “crunching the numbers for the customer,” Mills notes.
“At the end of a year, it would yield them a huge savings,” he continues. “While some mold designs for some molding processes drive up the cost of the tooling, it’s a case of ‘pay me now or pay me later.’ The more effort that is put into the project up front, the more efficient the molding process becomes, resulting in higher-quality components at lower cost. In the long run, it will allow the customer to optimize their ROI.”
Presenting the options
Despite its collaboration and education efforts, Xten often struggles to convince its customers of the optimal way a product should be manufactured. To help make its case, it provides customers with scenarios—how capacity can be increased, ways to increase productivity, and how secondary operations add costs to the project with limited benefits, in some cases. “One of the services we offer is a cost-down program in which we provide ways that customers can ultimately save money on their product either by combining parts, consolidating resins to make larger buys, or using regrind and much more,” explains Mills.
Consolidating parts offers big savings to both OEMs and molders. Dirr says that Xten recently completed a project in which it redesigned a part for sonic welding. “We were asked to make three parts—a base, cover, and another small cover that holds a magnet in place,” says Dirr. “We chose sonic welding to give us a hermetic seal around the small cover so the magnet doesn’t rust.
Next, we chose to make the smaller cover in the same mold with the larger cover [Xten routinely uses a Moldflow analysis performed by an outside vendor to make sure that the parts fill at the same time], and chose to make three components instead of two, making an additional small part and molding three at a time instead of two, which would allow us to be even more efficient and not have to run extra parts.”
Dirr adds that Xten’s success starts at the design engineering level as the company tries “to do as much as we can for the customer, and that includes always looking at ways to design a more efficient product.”
You can also read Chapters 1 and 2 by searching for “Xten.” —Clare Goldsberry