RIM Process & Material Comparisons
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Design Octaves RIM Sample Parts in Both 3mm and 6mm Nominal Wall Thickness are Rated 94V-0
Design Octaves RIM Advantages vs. Thermoforming
Here are some advantages of Design Octaves RIM (Reaction Injection Molding) process compared to thermoforming:
1. Core & Cavity Molding: All details are molded in place. We do not perform any secondary machining or bonding operations. You will get the same part every time. You don't run the risk of machining a feature incorrectly, forgetting to machine a feature, gluing something in crooked, etc. If you have ribs and bosses on the part, they will be molded-in. If you have undercuts, we will mold them in place.
2. Inserts: All brass threaded inserts are molded-in with Design Octaves Parts. The Design Octaves method provides better pull-out strength than post fitting methods typically found in formed parts. Also, the Design Octaves method provides for 100% of inserts to be straight and at the specified depth. All threads are clean and ready to use with this method.
3. Material Thickness: We mold consistent material thickness. When a deep part is thermoformed, the wall thickness at the corners of the deepest areas will be very thin, and even break through. With Design Octaves parts, you will have consistent wall thickness throughout the part, and you can have thick and thin walls where needed.
4. Thick Sections: Design Octaves can mold thick sections on parts where required for strength or industrial design intent. With thermoforming you are limited by the initial sheet thickness of the material.
5. Rigidity: Our parts are more rigid, and more dimensionally stable due to the physical properties of our material. Our rigid polyurethane material has an excellent strength to weight ratio.
6. Insert Molding: We can encapsulate many different materials. In addition to threaded brass inserts, you can have sheet metal, machined components, or magnets, molded in place. With thermoforming, those types of components would have to be glued in place which increases the chance of part failure.
Design Octaves RIM process vs. Cast Urethane Process
Most cast urethane parts are molded utilizing silicone rubber tools. RTV Molding, as that process is referred to, is really meant to be a prototype process, due to the high part cost. The rubber tools can only last from 20 to 50 parts, depending on the geometry. The urethanes they use attack the tooling rubber, making it brittle. If the client is molding 50 parts per year, this process can work OK, but once you get to the 100-200 per year volume, the tooling cost can far exceed the cost of our Composite Epoxy Tools. The RTV molder will need to cast a new tool after every 20 to 50 pieces and the silicone rubber they use is very expensive.
1. Part Cost: Since the cycle times are so long for cast urethane parts (sometimes only one or two parts per day) the part cost will be high. Our RIM parts are less expensive.
2. Tooling Cost: Our tools will be more cost effective when running at more than 100 parts per year. With Design Octaves, you only need to buy 1 tool, since we guarantee our tooling for a minimum of 10,000 cycles.
3. Dimensional Stability: Our parts will be much more stable and repeatable. The cast urethane parts can vary greatly since they are molded in rubber tools. Our standard part tolerance is +/- .010” up to 5.00”, and then .001” per inch added for every inch over 5.00”. We routinely hold this tolerance on parts up to 65”.
4. Material Properties: Our material will be more heat resistant than the cast urethane material. Our parts are generally quite a bit lighter as well – we mold our 6 mm wall system in the 45-50 pounds per cubic foot range. Both of the rigid polyurethane systems we mold with are UL 94V-0 rated for flammability. There are cast urethanes that are UL rated, but not many. Urethane parts are very susceptible to warping.
5. In-House Painting: We paint all of our parts in our designated paint shop. We lightly abrasive blast every part before painting which provides outstanding paint adhesion. Cast urethane parts can have problems with peeling paint, and we have absolutely no problems with paint adhesion. We have tight controls on all incoming paint and we have a very thorough paint validation and inspection process in place. We inspect every new batch of paint using our light box and gloss meter and we even have a spectrophotometer for the most challenging colors.
6. Overall Appearance: Our parts will be very consistent for color, gloss, and texture. We have an excellent process in place to control our paint. Cast urethane parts can vary widely from batch to batch. Our paint finishes have to match sheet metal parts, thermoformed parts, etc. that have been painted by other suppliers, and we have no problem matching these.
Contact Design Octaves for your RIM Molding Project
Do you have a project that requires reaction injection molding? We create high-end, limited-run RIM enclosures and have worked across industries. Contact Design Octaves today to tell us about your project or request a quote.