Thermoset Resins (resin and hardener combinations) are used in many industries, to form an endless variety of parts of all shapes and sizes, for a vast array of applications.
In some industries, the term RIM – an acronym for Reaction Injection Moulding – is used.
Most commonly Polyol and Isocyanates are mixed to cure and create Polyurethane parts. Other specialty resins are also used to mould and cast parts where their specific properties are required.
The resins mixing ratio (ratio of resin to hardener), viscosities of both components, the required output (mould size), and the pot life (how quickly the resin sets), are some of the key considerations when specifying the correct dispensing equipment for moulding and casting applications.
Different resins are selected to give the desired (shore) hardness of the finished part. Fire Retardant and Fiber Reinforced Resins are used in some demanding applications. And decorative surface finish can be achieved with a reverse imprint in the mould.
Moulds can be made from a variety of materials, but most commonly from; steel, aluminum, model board, or silicone, each with its own advantages and relevance depending on application and duty cycle.
The range of applications for moulded and cast parts is endless, and so too is the range of colours those parts are desired in. Pigments can be premixed into the polyol prior to dispense or injected as a ‘third component’ at the point of dispense.
The quality of the finished parts is dependent on the quality of the mix of resin and hardener, any imbalance (phasing) in the mixture can cause defects in the finished part. So, having quality and correctly specification dispensing equipment is critical to the quality of the finished moulded or cast parts.
Good machine specification and intelligent controls (software) enable the dispensing of various resins (with broadly similar properties) from a single dispensing machine, greatly increasing production flexibility.
The final mixing of the components at the point of dispense is done with; static mixing nozzles, rotor mixing nozzles, or a dynamic mixing head, depending on machine specification and customer preference.