California is one of the most important manufacturing markets in the United States, supporting medical devices, aerospace and defense, automotive and EV, electronics, biotechnology, consumer products, food and beverage, packaging, industrial equipment, and renewable energy.
For OEM engineers, product developers, sourcing professionals, and purchasing managers searching for the top rated mold making companies in California in 2026, the right supplier is not simply the one with the lowest tooling quote. Mold design, DFM, mold flow analysis, tool construction, sampling, qualification, repair, maintenance, and production support can all affect part quality, uptime, tooling life, and total manufacturing cost.
Hi-Rel Plastics & Molding Corp. is a Riverside, California plastics manufacturer supporting OEMs with custom mold making and tool manufacturing, plastic injection molding, tooling engineering, mold transfer, mold repair, mold maintenance, secondary operations, assembly, and contract manufacturing.
With more than 40 years of plastics manufacturing experience, Hi-Rel Plastics Riverside can support a program from engineering and DFM through mold manufacturing, sampling, production molding, ongoing tool maintenance, and finished assembly.
Hi-Rel also supports tooling across multiple plastics manufacturing processes, including:
Hi-Rel Plastics Riverside operates quality systems supported by ISO 9001:2015, ISO 13485:2016, and AS9100 Rev D, making its capabilities particularly relevant to quality-sensitive industries including medical, aerospace, defense, electronics, automotive, and industrial manufacturing.
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A strong mold manufacturing partner should understand how product geometry, resin selection, tooling, molding equipment, processing conditions, expected production volume, and quality requirements work together.
Important capabilities can include:
A mold is a long-term production asset. Buyers should therefore evaluate more than initial tool price and consider the supplier’s ability to support the entire tooling lifecycle.
The companies below are not presented as an independently audited numerical ranking. They are established California mold making and tooling resources that OEMs may evaluate based on publicly available capabilities, locations, services, and industry experience.
Hi-Rel Plastics Riverside combines mold and tool manufacturing with DFM, Mold Flow Analysis, mold transfer, mold repair, mold maintenance, injection molding, multiple plastics processing technologies, secondary operations, assembly, and contract manufacturing.
Its ISO 9001:2015, ISO 13485:2016, and AS9100 Rev D quality systems, together with support for medical, aerospace, defense, electronics, automotive, and other demanding markets, allow OEMs to consolidate tooling and production requirements with one manufacturing partner.
Best suited for: OEMs seeking a California tooling and plastics manufacturing partner for new molds, transferred tooling, multiple molding technologies, regulated industries, and turnkey production programs.
Westec Plastics is a long-established Northern California injection molding and mold manufacturing company focused on precision tooling, mold repair, refurbishment, machining, and lifecycle tooling support.
Best suited for: medical, biotech, electronics, and precision molding programs requiring in-house mold manufacturing and long-term tooling support.
JG Plastics Group supports precision mold making alongside thermoplastic and thermoset molding, insert molding, overmolding, cleanroom manufacturing, assembly, and secondary operations.
Best suited for: precision tooling programs serving medical, aerospace, defense, electronics, and other highly engineered applications.
JATCO supports mold construction, tool maintenance, mold modification, injection molding, assembly, decorating, packaging, warehousing, and distribution from its California manufacturing operation.
Best suited for: companies seeking tooling plus high-volume molding and broader downstream manufacturing support.
Fischer Mold is a Southern California tooling and injection molding company supporting prototype tooling, low-volume and high-volume molds, and ongoing production molding.
Best suited for: Southern California OEMs needing in-house injection mold building and production support.
A&S Mold and Die provides injection mold tooling, mold manufacturing, repair, design, engineering, machining, EDM, grinding, inspection, and plastic injection molding.
Best suited for: precision mold manufacturing, mold repair, and injection molding programs in Southern California.
KS Plastic supports precision tooling, injection molding, rapid prototyping, contract manufacturing, secondary operations, and program management in Northern California.
Best suited for: Bay Area OEMs seeking tooling combined with molding and contract manufacturing support.
Trademark Plastics provides mold design, tooling, DFM, validation, prototype tooling, production tooling, and injection molding with a strong focus on healthcare and medical-device manufacturing.
Best suited for: medical and healthcare programs requiring tooling, validation, and production support.
When evaluating California mold manufacturers, purchasing teams should compare the supplier’s ability to support the full production lifecycle.
| Evaluation Area | Why It Matters |
|---|---|
| Mold design | Influences part quality, reliability, and manufacturing efficiency |
| DFM | Identifies manufacturing concerns before tooling investment |
| Mold Flow Analysis | Helps evaluate resin flow and potential molding issues |
| Prototype tooling | Supports product development and design validation |
| Production tooling | Provides durability for sustained manufacturing |
| Multi-cavity tooling | Can increase output and reduce part cost |
| Hot runner expertise | Can reduce runner waste and improve production efficiency |
| Mold sampling | Verifies tool performance before production |
| Mold repair | Extends usable tooling life |
| Mold maintenance | Helps reduce unexpected production downtime |
| Mold transfer | Allows existing tooling to move to a new supplier |
| Production molding | Simplifies transition from tooling to manufacturing |
| Quality certifications | Important for regulated and quality-critical industries |
| Secondary operations | Reduces the number of outside suppliers required |
| Assembly | Supports more complete contract manufacturing |
Traditional tool shops may focus primarily on building the mold. Hi-Rel Plastics Riverside supports a broader manufacturing path:
Product Concept → Engineering & DFM → Mold Flow Analysis → Mold Design & Manufacturing → Mold Sampling & Qualification → Production Injection Molding → Secondary Operations → Assembly → Mold Maintenance & Repair
This integration matters because the supplier supporting the tooling also understands how the mold must perform once it enters production.
For OEMs with multiple plastic components, Hi-Rel can also support tooling and manufacturing across injection molding, LSR molding, blow molding, thermoforming, vacuum forming, and rotational molding.
Discuss Your Tooling or Mold Transfer Project with Hi-Rel
The terms mold making, injection mold manufacturing, mold building, tool making, tooling manufacturing, and plastic tooling are often used interchangeably.
An injection mold is tooling specifically designed to produce plastic components through injection molding. The broader term tooling can also include molds, dies, fixtures, trim tools, inserts, and production equipment used for LSR molding, blow molding, thermoforming, vacuum forming, and rotational molding.
For OEM buyers, the more important question is whether the supplier understands the manufacturing process for which the tool is being designed and can support that tool after production begins.
A poorly engineered mold can contribute to flash, sink marks, short shots, weld lines, warpage, ejection problems, uneven filling, long cycle times, premature tooling wear, maintenance issues, and inconsistent dimensions.
For this reason, mold development should ideally integrate product design, DFM, Mold Flow Analysis, material selection, tool design, mold manufacturing, molding-process knowledge, and quality requirements.
The lowest initial tooling price does not necessarily produce the lowest total manufacturing cost.
Tooling should be matched to expected production requirements.
Designed primarily for product development, design validation, testing, and limited quantities.
Provides an intermediate solution between prototype tooling and full production tooling.
Designed for products with modest annual demand where tooling economics are especially important.
Built for extended production life, repeatability, production reliability, and potentially very high cycle counts depending on construction and operating conditions.
California mold makers may also use SPI mold classifications from Class 105 through Class 101 to communicate expected tooling construction and production requirements.
OEMs do not always need a new mold. Existing tools may need to move because of supplier performance, quality issues, delivery problems, manufacturing consolidation, reshoring, capacity limits, supplier closure, or the need for stronger production support.
Hi-Rel Plastics Riverside can support existing molds through evaluation, sampling, repair, modification, refurbishment, qualification, and production where required.
A capable mold transfer partner should be able to:
For some OEMs, transferring a usable tool can provide a faster path to a new manufacturing relationship than constructing replacement tooling.
Even a properly designed mold requires ongoing maintenance. Repeated thermal and mechanical cycling can eventually cause tooling components to wear.
Maintenance areas can include:
Hi-Rel Plastics Riverside supports mold inspection, repair, modification, preventive maintenance, component replacement, refurbishment, engineering changes, and production support based on the condition and requirements of the tool.
This lifecycle support allows OEMs to evaluate Hi-Rel not only as a new mold manufacturer, but also as a potential long-term tooling and production partner.
Liquid Silicone Rubber requires tooling considerations that differ from conventional thermoplastic injection molding.
LSR injection molding may require particular attention to:
Hi-Rel Plastics Riverside supports both LSR tooling and LSR injection molding, helping simplify the transition from tool development to production for suitable medical, electronics, sealing, industrial, and consumer applications.
Not every plastic product is injection molded. Bottles, reservoirs, containers, ducts, packaging, and other hollow products may require blow molding and blow mold manufacturing.
Hi-Rel supports tooling for:
This broader capability can be useful for OEMs with multiple plastic products that require different molding technologies.
Thermoforming and vacuum forming require different engineering considerations from injection molding, including heating, material draw, vacuum flow, draft, cooling, trimming, plug assists, and dimensional shrinkage.
Hi-Rel supports thermoforming and vacuum forming tooling for applications such as medical trays, packaging, housings, transportation components, covers, industrial products, and consumer products.
Rotational molding is commonly used for larger hollow plastic products such as tanks, containers, housings, enclosures, industrial products, recreational products, and specialty components.
Hi-Rel supports rotational molding tooling and production, extending its tooling capabilities beyond conventional injection molding.
For California OEMs, working with a regional tooling and manufacturing company may provide advantages during engineering, tool sampling, qualification, production launch, repair, and ongoing production.
Potential benefits include:
Southern California manufacturing markets include Los Angeles, Orange County, Riverside, San Bernardino, the Inland Empire, and San Diego, while Northern California includes San Jose, Silicon Valley, the San Francisco Bay Area, Fremont, Oakland, and Sacramento.
Before issuing a tooling purchase order, OEM buyers should consider asking:
The answers can help distinguish a basic tool builder from a long-term mold manufacturing and plastics production partner.
Yes. Hi-Rel supports custom mold making and tool manufacturing for injection molding programs, including prototype, bridge, low-volume, medium-volume, and production tooling requirements.
Yes. Hi-Rel can incorporate Design for Manufacturability and Mold Flow Analysis into the tooling development process to help evaluate part geometry, gate placement, resin flow, filling behavior, cooling, shrinkage, weld lines, air traps, and potential warpage before tooling is finalized.
Yes. Existing molds can be transferred for evaluation, sampling, repair or modification where required, qualification, and ongoing production.
Yes. Hi-Rel supports mold inspection, repair, modification, preventive maintenance, refurbishment, engineering changes, and production support based on the requirements and condition of each tool.
No. Hi-Rel supports tooling associated with injection molding, LSR molding, EBM, SBM, ISBM, thermoforming, vacuum forming, and rotational molding.
Yes. Hi-Rel combines tooling capabilities with production injection molding, secondary operations, assembly, and broader contract manufacturing support.
Hi-Rel Plastics & Molding operates quality systems supported by ISO 9001:2015, ISO 13485:2016, and AS9100 Rev D.
Hi-Rel Plastics & Molding is located in Riverside, California and supports customers throughout Southern California, Northern California, and across the United States.
Choosing a mold manufacturer is a long-term production decision. The right partner should understand how to design and manufacture the tool, how to qualify it, how to maintain it, and how it must perform throughout production.
Hi-Rel Plastics Riverside supports OEMs with mold and tool manufacturing, mold transfer, mold repair, maintenance, injection molding, LSR molding, blow molding, thermoforming, rotational molding, secondary operations, assembly, and contract manufacturing.
With more than 40 years of plastics manufacturing experience and ISO 9001:2015, ISO 13485:2016, and AS9100 Rev D quality systems, Hi-Rel can support projects from DFM and tooling through production and ongoing mold lifecycle support.
