Painted Rhino Inc.

How it's done...

Hot off the press

We are expanding soon to a additional 50,000sqft. facility.

A composites industry Leader

The Heavy Gauge Thermoforming Process:
Heavy Gauge Thermoforming is the heating of extruded thermoplastic sheet, and applying a force (vacuum and/or pressure) to form the sheet into or over a mold. Heavy Gauge Thermoforming can be subcategorized into three specific processes – Vacuum Forming, Pressure Forming, and Twin-Sheet Forming. The starting gauge of plastic sheet is between 0.060" to 0.50".

Thermoplastic sheet can be manufactured to suit a wide variety of "end use" requirements. Properties such as color, rigidity, UV resistance, low temperature impact, heat distortion temperature, etc. can be optimized in a cost effective way to add value to the part. Post molding, the formed parts are required to be trimmed from the sheet in a secondary process using 5 and 6 axis CNC robotic trimming equipment, or molds can be equipped with trim landing to utilize a hand held router.

Vacuum Forming

In the Vacuum Forming process, a single sheet of extruded plastic is heated to a softening point at which time vacuum (14.7psig) is applied to pull the sheet over a male tool, or into a female tool. Vacuum Forming is the most basic of the three thermoforming processes. This is generally due to the demand for low cost tooling, design flexibility, and shorter lead times. Since the cosmetic side of the part is on the non-tool surface of the sheet, a wide variety of surface textures or printed features are available.

Advantages of Vacuum Forming: Low cost tooling.
Quick turn-around for parts.
Easy tool modification, if necessary.
Wide variety of materials, colors, and textures are available.

How does the Reaction Injection Molding urethane (RIM) process work?

Two liquid components, an isocyante and a polyol are placed in holding tanks. They are conditioned to the correct temperatures (approximately 100 degrees F), pressures and specific gravities. The dispensing unit pumps the correct amounts and ratios of these liquids into the mold during the injection phase of the molding cycle. During the molding process, the unit continuously circulates the isocyante and the polyol at low pressures to keep them uniformly conditioned.

Time To Inject

When it is time to inject the two liquids into the mold the dispensing unit switches to a higher pumping pressure. The isocyanate and the polyol are injected via a special valve called a mix head. The mix head ensures complete mixing of the two liquids. At this time the chemical reaction begins as the mold is being filled with liquid polyurethane. The mold must be filled within 5 to 35 seconds depending on which polyurethane we are using. There is little if any expansion to most of the polyurethanes we process. The chemical reaction between the isocyanate and the polyol creates exothermic heat. Temperatures may reach 250 to 350 degrees momentarily in the mold. Pressures seldom rise above 25 to 50 psi in the mold.

Numerous Advantages to Reaction Injection Molding (RIM)

The very low molding pressures and temperatures for Reaction Injection Molding (RIM) give it numerous advantages:
Low cost tooling that is economical for low production volumes and/or large parts.
Economical set-ups for short production runs make Reaction Injection Molding (RIM) well suited to JIT deliveries for even low production volumes and Kan Ban.
Designers have more creative opportunities with Reaction Injection Molding (RIM) because it can easily mold thin and thick walls in the same part.
Insert molding and encapsulation of delicate components is much easier with Reaction Injection Molding (RIM) because pressures and temperatures are low. This can reduce your assembly costs, make assemblies tamper-proof or solve sealing problems for you.

The RIM Urethane process:

The vacuum form and thermoform process