CUSTOM MOLDED RUBBER
When a standard part just won’t do, we have the expertise to help.
In addition to the wide variety of standard sealing devices we offer, RL Hudson can also assist you with those non-standard applications that require something special. In fact, designing custom molded rubber parts is one of the things we do best. Our experienced engineering department uses Pro/ENGINEER“ solid modeling software to translate the size and shape specifications you provide into a highly detailed drawing. We can then suggest a compound that’s suited for your operating environment. The number of parts you need and when you need them will also help us determine how best to complete your project.
Once all of the design elements have been considered, the mold (tool) itself will be built. This mold will consist of two or more steel plates custom-machined so as to achieve proper alignment (registration) and surface finish. The precise number and configuration of the plates vary depending on the molding method, and there are three main methods to choose from: compression, transfer, or injection molding. Though these methods are similar in that they all utilize heat and pressure to vulcanize (cure) rubber parts, they also differ in some important ways.
Compression molding involves putting the uncured rubber compound into a heated, open mold cavity, then closing the mold under pressure (usually in a hydraulic press) to initiate vulcanization (see Figure 1). In transfer molding, the uncured rubber compound is first placed in a transfer chamber (pot), heated, then squeezed down through a sprue, runner, and gate system leading into a closed mold cavity (see Figure 2). Injection molding is so named because the preheated rubber is injected under pressure through a runner system and into a closed, heated mold (see Figure 3). Because injection and transfer molds stay closed throughout the molding process, they typically produce more intricate and consistent parts than compression molds. Though they’re more expensive to operate than compression molds, transfer and injection molds also allow for higher temperatures and shorter cure times, thus reducing finishing costs.
Questions invariably arise, so please allow plenty of lead time to avoid costly delays. From the point at which you approve our drawing, it typically takes about eight weeks to design and produce a mold, then produce first articles (samples from each cavity in the mold). Once these first articles have been tested and approved for service, it generally takes six to eight weeks to receive the first production lot. These are typical lead times, but we’ll work with you in every way possible to meet your schedule.
One final note: Don’t be fooled by needlessly complex designs. The most exotic design in the world is useless if it cannot actually be produced. We at RL Hudson understand this, and we make it our business to provide you with economical, high-quality parts designed so that lot after lot will consistently meet your requirements. We’d like to help you attain this kind of consistency with your next custom molded rubber part.