Rubber moulding processes:
At RH Nuttall we have a wealth of experience in the production of rubber mouldings. Our specialist design team are always on hand to talk through the best method of having your rubber moulded parts produced. Volume, tooling, and speed are all balanced out in order to achieve the most economical option.
The three main processes we manufacture our rubber moulded parts from are briefly described below, however if you are in need of advice, please feel free to speak to one of our sales team members who are always on hand to help.
Transfer Rubber Mouldings – A simple pot/plunger method of producing larger volumes of cleaner cut rubber components. Precise amounts of uncured rubber are weighed and placed into cavity (transfer pot) tooling. The closed moulding tool is then sealed and pressure applied, forcing the rubber through from the pot and into the shaped tool. The rubber part produced must be cured prior to removal and therefore the tooling is held in situ until this occurs. The moulding tool is then opened and the formed rubber part removed. The deflashing process then begins with the removal of any excess particles from the extremity of the component. This is often done with a knife or scissors. Transfer moulding of rubber parts generally minimises the need for excess flash and material compound wastage. The advantage of this method of production is the speed of having the parts produced, however this has to be balanced with the initial cost of multi cavity, and sometimes more complex tooling. Generally considered for mid/high volumes.
Compression Rubber Mouldings – Top and bottom single or multi cavity steel tool process. Precise measurement of compound is inserted into preheated tool, allowing for the correct flow of heat and pressure, and thus reducing the excess material (flash) having to be trimmed upon completion. The tooling is closed and heated to the correct temperature to produce the finished rubber moulding. Bespoke tooling is made to the desired shape required. This can range from a few hundred pounds for small, basic shape, single cavity tooling, to a few thousand pounds with larger cell, and more intricate parts. The main disadvantage to this process is that it can be more time consuming due to reloading times, when compared to injection moulding for example.
Injection Rubber Mouldings – Generally used with our high volume rubber moulding output. Uncured rubber is inserted into the automated injection unit leading to the nozzle. A precise amount of compound is plasticised, heated to the desired level, and then drawn through into the nozzle. Naturally this in then dispensed with accurate amounts pushed though into the moulding cavity below though a runner system. Automatic levels of temperature and pressure are applied to the cavity tooling until the rubber moulding cures and becomes vulcanised. Set up times, in conjunction with tooling costs, must be considered for this process.