Inside Hi-Rel Plastics & Molding Corp.: A injection molding Manufacturer Built on Precision and Pride
The hum starts before you see anything. Walking into Hi-Rel Plastics & Molding Corp.'s Riverside, California facility, you hear the rhythm of injection molding presses cycling — that steady, mechanical cadence that serious shops develop over decades. Technicians in cleanroom gowns move with purpose past racks of just-inspected components. A CMM operator cross-references a medical housing against a digital model on a nearby screen. Nobody is rushing, but nobody is standing still either. This is what forty years of precision manufacturing looks like when it's working right.
Founded in 1985, Hi-Rel has spent four decades building the kind of reputation that doesn't come from marketing — it comes from delivering tight-tolerance parts to industries that cannot afford failures. Medical. Aerospace. Defense. These aren't forgiving customers. They don't take chances on vendors who can't back up their capabilities with hardware, processes, and certifications that mean something.
What They Build — and Who They Build It For
Hi-Rel specializes in custom plastic injection molding and liquid silicone rubber (LSR) molding, producing precision-engineered components for some of the most demanding end-use environments in American industry. Their work spans medical device parts, aerospace structural and interior components, defense housings, and complex secondary subassemblies that integrate multiple materials and finishes.
The customer base reflects the shop's capabilities directly. Medical device OEMs need parts with documented traceability, cleanroom production, and quality systems that align with FDA expectations. Aerospace primes need dimensional repeatability and material compliance backed by auditable records. Defense contractors need confidentiality, schedule reliability, and components that perform in environments nobody wants to think about. Hi-Rel checks all three boxes — simultaneously, on the same floor.
That's not a trivial achievement. Many shops carve out a single vertical and optimize for it. Hi-Rel has built infrastructure and a quality management system capable of serving all three at once, which speaks to the depth of their operational discipline.
Certifications That Carry Weight
In precision manufacturing, certifications aren't window dressing — they're evidence of how a shop actually operates. Hi-Rel holds ISO 9001:2015, the baseline quality management standard. They also hold ISO 13485:2016, the medical device-specific quality standard that governs everything from process validation to complaint handling. And they carry AS9100D, the aerospace and defense quality management standard that demands risk-based thinking, configuration control, and first-article inspection rigor.
Maintaining all three concurrently requires a quality infrastructure that most shops their size don't attempt. It means separate documentation systems, cross-trained quality personnel, and the organizational discipline to keep each program current through regular surveillance audits. For procurement managers sourcing into regulated industries, this triple certification stack is a meaningful differentiator — it reduces your supplier qualification burden and signals a shop that takes compliance seriously as a business strategy, not a checkbox exercise.
Technology on the Floor
Hi-Rel runs injection molding presses alongside dedicated LSR molding machines — a combination that gives them material flexibility most single-discipline shops can't match. Liquid silicone rubber is a specialty process. It demands precise temperature control, specialized tooling with tight shut-off tolerances, and process parameters that behave differently from thermoplastics. Shops that run LSR well have typically invested years in developing that competency. Hi-Rel has.
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Their tooling and mold fabrication capabilities allow them to bring tool development in-house, which shortens lead times and gives their engineers direct control over the tooling that determines part quality. Pair that with mold flow analysis during the design phase, and you have a shop that can catch problems before steel is cut — a significant cost avoidance for customers bringing new programs online.
On the inspection side, CMM inspection and advanced metrology give their quality team the ability to fully characterize complex geometries and provide customers with dimensional data that holds up under scrutiny. In industries where first-article inspection reports are mandatory and PPAP packages need to be bulletproof, this matters.
The cleanroom manufacturing and assembly capability is purpose-built for medical and high-sensitivity applications. Not every molding shop has a functional cleanroom. Those that do have made a capital commitment that tells you something about the customer base they intend to serve long-term.
What Makes This Shop Different
A lot of molders can quote you a price. Fewer can take a concept from a napkin sketch through DFM review, mold flow simulation, tool fabrication, validated production, cleanroom assembly, and final packaging — under one roof, with a single quality system governing all of it.
Vertical integration is Hi-Rel's real differentiator. Their service offering runs from initial concept and design for manufacturability (DFM) analysis through final assembly and packaging. For a medical device startup or an aerospace supplier managing a complex BOM, that kind of end-to-end capability reduces program risk, simplifies communication, and eliminates the handoff errors that cost money and time when work moves between separate vendors.
Fifty to ninety-nine employees puts Hi-Rel in a scale range that procurement teams sometimes underestimate. This isn't a garage operation. It's a mature, staffed, capitalized manufacturer with management systems sophisticated enough to serve Tier 1 aerospace suppliers and FDA-regulated medical device companies. At the same time, it's not so large that your program disappears into a backlog. Program managers return calls. Engineers engage directly with customer teams. That combination of capability and accessibility is genuinely harder to find than it should be.
For sourcing teams doing their initial research, hirelplastics.com lays out their full capability stack with enough technical detail to make a preliminary qualification assessment without picking up the phone first.
About Hi-Rel Plastics & Molding Corp.
- Founded: 1985
- Location: Riverside, California
- Employees: 50–99
- Specialties: Custom plastic injection molding, LSR molding, cleanroom manufacturing and assembly
- Certifications: ISO 9001:2015, ISO 13485:2016, AS9100D
- Markets Served: Medical devices, aerospace, defense, industrial
- Key Capabilities: DFM, mold flow analysis, tooling fabrication, CMM inspection, cleanroom production, final assembly and packaging
- Website: Visit Hi-Rel Plastics & Molding Corp.
Where to Find Them
Hi-Rel Plastics & Molding Corp. is based in Riverside, California, within the broader Southern California industrial corridor that has long supported aerospace and defense manufacturing in the region. Their location gives them logistical proximity to major aerospace primes and medical device OEMs throughout Southern California while maintaining the ability to serve customers nationally.
Procurement managers, engineering leads, and operations teams evaluating injection molding partners for regulated industries should start their due diligence at Visit Hi-Rel Plastics & Molding Corp., where capability documentation, certification details, and contact information are available directly.
Four decades in. Still building to spec. That's the Hi-Rel story — and it's the kind of story American manufacturing needs more of.
