Engineered Materials We Fabricate for OEM and Industrial Applications
Wm. F. McGraw & Co. is a Riverview, Michigan fabricator of engineered materials for the electrical, power, aerospace, EV, medical, and industrial OEM markets. We fabricate one of the broadest engineered-material catalogs in the region — thermoplastics, the full glass-epoxy laminate family, phenolics in three reinforcements, switchgear-grade GPO-3, and specialty thermal products like Glastherm® HT and SG-200.
We don’t just stock material. We cut, machine, route, drill, and finish it to your drawings, in volumes from one-off prototypes to repeat production runs. This page is your starting point for every material we work with.
How to Choose the Right Material
Most material decisions come down to four questions. Your answers point to one or two strong candidates from our catalog.
- What is the primary load on the part? Electrical (dielectric strength, arc resistance) → GPO-3, G-10, FR-4, G-11. Thermal (compressive strength under heat) → Glastherm® HT or SG-200. Mechanical or optical → polycarbonate, acrylic, acetal, nylon, or phenolic.
- What’s the operating temperature? Acrylic and polycarbonate top out near 240°F. G-10 and FR-4 perform to roughly 285°F. G-11 pushes higher. G-7 silicone runs continuously to 428°F. Glastherm® HT is engineered for service to 550°F.
- Does the part need flame retardance, arc resistance, or a UL rating? FR-4 (flame-retardant glass epoxy), GPO-3 (UTR arc/track + flame), and G-9 (arc resistant melamine) are built for it.
- What’s the production volume and tolerance? We support one prototype through repeat production with tight machined tolerances or simple cut-to-size jobs.
Not sure where to start? Send us your drawing or a description of the application — our team will scope the material options before you commit.
Materials at a Glance
A quick comparison of the engineered materials we fabricate. Click any material below for full specs, fabrication options, and typical applications.
| Material ▲▼ | Family ▲▼ | Best Known For ▲▼ | Typical Use ▲▼ | Top Industries ▲▼ |
|---|
Our Material Catalog
Thermoplastics
Our shop fabricates a broad range of custom plastic components for electrical and thermal applications, including:
Polycarbonate
The impact-resistant thermoplastic — roughly 250 times stronger than glass at half the weight, with broad chemical resistance and excellent machinability. Used for guards, viewing windows, protective shields, and structural covers across EV, medical, and industrial applications. Read more about Polycarbonate Fabrication.
Acetal (Delrin®-class)
Engineering-grade thermoplastic with low friction, high dimensional stability, and excellent machinability. The go-to material for bushings, gears, precision wear parts, and small machined components where moisture absorption needs to stay low. Read more about Acetal Fabrication.
Acrylic
Nylon
Tough, abrasion-resistant thermoplastic with strong wear characteristics. Cast nylon delivers the best machined performance for bearings, slides, sheaves, and structural parts in industrial, motor, and transit equipment. Read more about Nylon Fabrication.
Glass Epoxy Laminates: G-10, FR-4, G-11
Glass epoxy laminates combine fiberglass reinforcement with epoxy resin to deliver dielectric strength and structural rigidity in the same part. We fabricate all three industry-standard grades.
G-10 Glass Epoxy
The standard glass-epoxy laminate — high dielectric strength, exceptional mechanical performance, low moisture absorption. Used for bus bar supports, standoffs, terminal boards, and structural insulators across switchgear and power electronics. Read more about G-10 Fabrication.
FR-4 (Flame-Retardant Glass Epoxy)
G-10 with flame-retardant chemistry — same mechanical and dielectric performance, with the flame rating required for UL-classified electrical enclosures, PCB substrates, and safety-critical components. Read more about FR-4 Fabrication .
G-11 Glass Epoxy
G-10’s high-temperature cousin — same family, with a resin system that holds mechanical and dielectric performance at higher continuous service temperatures. Used where G-10 would soften but a thermoset is still needed. Read more about G-11 Fabrication.
High-Temperature Laminates: G-7, G-9
Glass epoxy laminates combine fiberglass reinforcement with epoxy resin to deliver dielectric strength and structural rigidity in the same part. We fabricate all three industry-standard grades.
G-10 Glass Epoxy
The standard glass-epoxy laminate — high dielectric strength, exceptional mechanical performance, low moisture absorption. Used for bus bar supports, standoffs, terminal boards, and structural insulators across switchgear and power electronics. Read more about G-10 Fabrication.
FR-4 (Flame-Retardant Glass Epoxy)
G-10 with flame-retardant chemistry — same mechanical and dielectric performance, with the flame rating required for UL-classified electrical enclosures, PCB substrates, and safety-critical components. Read more about FR-4 Fabrication .
G-11 Glass Epoxy
G-10’s high-temperature cousin — same family, with a resin system that holds mechanical and dielectric performance at higher continuous service temperatures. Used where G-10 would soften but a thermoset is still needed. Read more about G-11 Fabrication.
G-7 Glass Silicone
Glass-cloth laminate with a silicone resin system — engineered for continuous service to roughly 428°F. Used for arc shields, high-temperature insulators, and components in generators and high-output motors where epoxy laminates would degrade. Read more about G-7 Fabrication.
G-9 Glass Melamine
Glass-cloth laminate with a melamine resin — built specifically for arc and flame resistance. Used in arc barriers, switchgear panels, and applications where flashover risk is the primary design constraint. Read more about G-9 Fabrication.
Phenolics: Paper, Canvas, Linen
Phenolic laminates are thermoset materials with a long industrial track record. The reinforcement determines the use case — and we fabricate all three.
Paper Phenolic
The most economical grade — paper-reinforced phenolic for general electrical insulation, structural panels, and light-duty mechanical components.
Canvas Phenolic
Cotton-canvas reinforcement gives this grade the impact resistance and machinability needed for gears, bearings, and bushings — the preferred phenolic for industrial mechanical parts.
Linen Phenolic
Fine-weave linen reinforcement produces a tighter, smoother finish — the right choice for precision gears, small machined components, and applications where surface quality matters.
Read more about Phenolic Fabrication
Switchgear-Grade Composites
GPO-3
UTR (UL Tracking Resistance) arc and track resistance combined with flame retardance — GPO-3 is the standard glass-polyester laminate for switchgear barriers, panels, mounting plates, and transformer hardware. We’ve been fabricating GPO-3 for decades; it’s one of our deepest specialties. [Read more about GPO-3 Fabrication →]
Specialty Insulation: SG-200 and Glastherm® HT
SG-200 Polyester Laminate
A flexible, high-temperature laminate used as perimeter mold insulation, motor and transformer wraps, and other applications where you need thermal performance in a form that bends instead of breaks. Often paired with Glastherm® on the same equipment. Read more about SG-200.
Glastherm® HT
Fiberglass-reinforced thermoset insulation engineered specifically for plastic and zinc die cast molds, plastic injection presses, and rubber molding equipment. Reduces heat loss into the press, stabilizes processing temperature, and survives continuous service to 550°F. We’ve been fabricating Glastherm® for the molding industry for decades. Read more about Glastherm® HT.
Industries We Serve
| Industry | Application |
|---|---|
| Aerospace | high-strength composites and dielectric components |
| Electric Vehicles | battery insulators, structural composites, thermoplastic guards |
| Generators | GPO-3, G-7, G-10 for stator supports, terminal boards, arc barriers |
| Medical | clear thermoplastics, machined housings, dielectric components |
| Motor Applications | slot insulation, phase insulation, structural composites, SG-200 wraps |
| Oil & Gas | chemical-resistant thermoplastics and high-temperature composites |
| Power Electronics | bus bar supports, standoffs, FR-4 enclosures, insulating barriers |
| Switchgear | GPO-3 panels, G-9 arc barriers, FR-4 mounting plates |
| Transformers | laminate insulators, phenolics, structural supports |
SPECIALIZING IN THE FABRICATION OF MOLD AND PLATEN INSULATION FOR THE PLASTIC INJECTION AND RUBBER MOLDING INDUSTRIES
Why Engineers and Manufacturers Trust WM McGraw
In-house fabrication, not just distribution
We're a fabricator first. CNC machining, precision cutting, drilling, routing, and finishing all happen under one roof in Riverview, Michigan. We control quality, lead time, and tolerance ourselves — instead of routing your job through a distributor's outside vendor.
Material expertise across families
Most fabricators are deep in one family. We work daily across thermoplastics, glass-epoxy laminates, high-temperature silicone and melamine grades, phenolics, GPO-3, and thermal insulation. That breadth means we can recommend the right material — not just the one we happen to stock.
The full glass-laminate family
Most competitors stop at G-10/FR-4 and GPO-3. We fabricate G-7, G-9, G-10, G-11, and FR-4 — the full grade range. If your application calls for a less-common grade, you don't have to compromise on the material to find a fabricator.
Specialty in mold and platen insulation
Plastic injection, zinc die cast, and rubber molding shops have come to us for decades for fabricated Glastherm® HT and SG-200 insulation, custom-cut and drilled to mold dimensions. If you run molding equipment, you've likely already used parts we made.
Engineered support, not just quotes
Send us a drawing, a sample, or a description of the application. We'll come back with material options, trade-offs, and a quote — not just a price on the part you specified, which may not be the right one.
Request a Materials Quote
Frequently Asked Questions
What materials does WMF McGraw fabricate?
We fabricate engineered thermoplastics (polycarbonate, acrylic, acetal, nylon), the full glass-epoxy laminate family (G-10, FR-4, G-11), high-temperature laminates (G-7 silicone, G-9 melamine), phenolics in paper, canvas, and linen reinforcements, switchgear-grade GPO-3, flexible SG-200 polyester laminate, and Glastherm® HT thermal insulation. If you don’t see your material listed, contact us — we likely work with it.
What's the difference between G-10, G-11, G-7, and G-9?
What's the difference between G-10 and GPO-3?
What does "UTR" mean on GPO-3?
UTR refers to the UL Tracking Resistance rating. GPO-3 grades carry strong UTR performance, which is why they’re chosen for high-voltage switchgear and transformer applications where surface tracking is a failure risk.
Do you fabricate prototypes or only production runs?
Can you machine to drawings or do you only cut to size?
How do I get a quote?
Send your drawing, specs, or a description of the application using the Contact Us form, email sales@wmfmcgraw.com, or call 734-281-1959. Most quotes turn around in one to two business days.
Do you ship outside Michigan?
Yes. We ship fabricated material nationally and internationally. Local pickup at our Riverview, Michigan facility is also available.
