California Injection Molding: Proven Strategies for Success

Performance Engineered Products Inc. (PEP) needs only to look up and down its street in Pomona, California, to grasp the inherent challenges that come with running a manufacturing facility in the Golden State. Once home to six injection molding firms, PEP is the last one standing on this particular stretch of Pomona Boulevard. Located at the edge of the Inland Empire, this one-time manufacturing hotbed has watched its injection molding influence wither under the state’s higher costs for land, labor and utilities, as well as greater regulatory burden.

PEP’s operations are split between this site in Pomona, with 33 injection molding machines, including three vertical presses, ranging from 33 to 500 tons in clamping force, and a 10-machine operation 15 miles away in Riverside with larger presses ranging in tonnage from 600 to 850. ISO 9001, 13485 and AS9100D certified, PEP generates 45% of its business from the aerospace sector — a market that entails running high-end materials, including around 3,000 to 4,000 pounds of Ultem polyetherimide (PEI), every month.

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PEP has begun program of updating its injection molding fleet, which includes vertical and horizontal presses. Source: (all) Performance Engineered Products

For Chirag Thummar, PEP’s VP of operations, the high costs of those high-temperature resins and the baked-in challenges of California make scrap unacceptable from a bottom-line business point of view.

Hired by PEP in 2020 as a design engineer, Thummar would stray from the front office for regular forays onto the shop floor. On these visits, he didn’t always like what he saw. “I would find out where people are missing time, waiting,” Thummar says. “For example, a technician would mold a sample part, but they were waiting almost two or three hours for quality to give approval.”

Over time, Thummar was promoted, first to general manager and then to his current role as VP of operations. In this position, he shared with PEP’s ownership examples of “missing time” and was given free rein to implement changes targeting inefficiency.

Starting With Startups

The shop-floor observations of Thummar and PEP’s operators quickly identified a culprit for wasted time: startups. In addition to the aforementioned disconnect between production and quality on first-part inspection, PEP isolated issues with material preparation and readiness.

“We calculated some of the startup scrap, and identified that most of the time material was not ready,” Thummar says. The underprepared material required purging, which consumed time and money. “For our 400- and 500-ton machines with bigger barrels, every time you purge the whole barrel, you’re losing like three or four pounds of material.” Quite often those resulting three- and four-pound “purge patties” weren’t commodity resins but high-priced engineering resins.

Components used in semiconductor packaging molded in PEP’s small molding press area. 

Starting in the summer of 2025, PEP began measuring moisture content in the materials before running them to address this waste.

“We decided to implement more drying discipline so that any technician or process engineer starting the machine needs to check the moisture first,” Thummar explains. “After the moisture check, they submit to quality; quality approves the moisture; and then they allow the technicians to start the machine and make some startup samples.”

Now PEP tests all resin moisture before startup, with hourly checks on parts. In addition, each press has a dedicated dryer paired to the machine based on its capacity and the capacity of the molding machine. Going forward, the company will add greater transparency and tracking capabilities, with the introduction of barcodes to the dryers and work orders for visibility on material prep in each process and job run.

PEP maintains around 1,500 active tools. 

Since implementing these changes, Thummar says PEP has cut startup time and scrap in half, with a reduction of customer part rejections and subsequent credits by a third. “Last month, we didn’t have any rejections from our customers,” Thummar says. “It looks like what we are doing is working; however, we still need to improve on the little stuff.”

Punishing Payroll  

One of the California-specific challenges that made molders scarce on PEP’s street was labor costs. According to the Economic Policy Institute based on 2024 data, California’s average hourly wage rate — $39.50 — was fourth highest in the U.S., trailing only Washington D.C., Massachusetts and Washington state, with the overall U.S. average at $35.06. (Mississippi’s $26.60 was the lowest).

For most molders, payroll represents 25-30% of their overhead, Thummar notes. PEP, however, was spending as much as 40% on payroll through temp agency staffing and direct employees.

A PEP employee exits the main molding floor. PEP has emphasized efficiency to maximize employee productivity. 

“Some of the startup times were almost four hours, with people sitting and waiting for a lot of that,” Thummar says. “We’re now using our people more efficiently, and we were able to reduce staff by almost 15%.”

Diverse Production

PEP has roughly 1,500 active tools and 400 customers, according to Thummar. When Plastics Technology visited, machines were fulfilling aerospace, automotive and medical orders, among others. Parts included a one-way check valve and the structural component of a commercial airliner’s toilet seat; an air-intake system and part of a fuel system for automotive customers; a pill packaging case with a living hinge and latch for a medical customer; a firefighter helmet from PC/PET; and a component for semiconductor packaging.

Production runs on a 24/5 schedule with 75 total employees in Pomona and another eight staff in production at the Riverside plant. In addition to Ultem, PEP processes other high-temperature materials, including polyether ether ketone (PEEK) and polysulfone (PSU), among roughly 200 different resins.

The Pomona facility includes a full tool room with the ability to make engineering changes in house, as well build some small inserts and complete tools — it will build 35 in 2026.

PEP operates 33 injection molding machines in Pomona, ranging in clamp force from 33-500 tons. 

In terms of secondary operations, PEP has an assembly area with epoxy bonding, sonic welding and heat-stake insertion. Many of its parts require some postmold machining, which PEP handles in house.

To further boost efficiency, the company will create cells featuring a press and a CNC machine in one shared space. Since Thummar joined, PEP has been investing in new molding machines to turn over aging presses in its fleet. Pomona will add four to five machines in 2026, including a 110-, 250- and 300-ton machine, with plans to install a 1,000-ton press in Riverside. From a quality perspective, PEP has in-house capabilities for pressure, leak, water and vacuum testing.

Moving Beyond Medical

While much of California is awash in supply for the healthcare industry, and PEP has been a long-time exhibitor at the medical-focused MD&M show in Anaheim, that segment has never been an outsize source of business for the company, despite its ISO 13485 certification. “We still get some medical leads, and we are very honest with our new clients,” Thummar says. “We don’t have a clean room; we don’t do the sterilized products.” PEP has found the bulk of its business across a diverse selection of other markets.

“Our big 15 customers are in a variety of industries,” Thummar says, noting that automotive and aerospace accounts have been growing by as much as 30% year over year. “We realized, these are the markets we need to focus on: electronics, aerospace, automotive OEM and some big consumer products.” Many of those “big 15” customers are Fortune 500 businesses, with PEP counting companies like Airbus, Boeing, Chrysler, Nissan, Samsung, Disney and Texas Instruments, as patrons.

PEP’s fully functional tool room gives the molder the ability to make engineering changes and build tools in house. 

At the MD&M show held in February, PEP saw a lot of booth traffic coming in the form of boomerang business with one-time customers seeking to engage with PEP once again. “We saw customers PEP used to mold for almost 10 years ago,” Thummar says. “Those customers came back to our booth and said they want to move their mold back to us. Near my area, I do see so many molding shops are closing because it’s so expensive here in California.”

Those heightened expenses make scrap doubly costly and add to the allure of a company like PEP with strong processing capabilities. Multiple leads from the show entailed transferring a mold. “We do like to do transfer molds a lot,” Thummar says. “PEP has very good engineering strength, and our technicians and process engineers are very good.”

One recent transfer tool was the aforementioned fire helmet, which had been experiencing scrap rates as high as 25% at its prior molder. Thummar says PEP dedicated a machine to the mold to help it determine the best process, which eventually involved customizing a nozzle specific to the job. “Now it’s running very smoothly,” Thummar says. “The customer is getting their parts, and they’re recommending our facility to others.”