Glossary of industry terms C to D
CAD - The acronym for Computer Aided Design.
CAM - The acronym for Computer Aided Manufacture.
Carousel - A rotational moulding machine design where the oven is normally located to the left, the cooling station to the right, and the service station at the front, with indexing taking place around a vertical axis shaft. The machine therefore resembles a fairground carousel, hence the name.
Cast - 1. To form a section of a mould tool by pouring a liquid metal (normally aluminium) into a cavity.
2. To form a section of a model or pattern by pouring a liquid resin into a cavity.
Casting - The finished product of the casting operation.
Casting contraction (casting shrinkage) - the allowance applied to the model or patterns used to make a cast mould tool to compensate for the shrinkage of the castings during cooling.
Cavity - The space inside a mould tool which forms the moulded product.
Centre guide assembly - The guide pin lines up the spider halves while the key prevents any rotation that could cause damage to parting lines.
Centre guide pin - Alignment device mounted to mounting hub to aid in opening and closure of mould spider/frame.
Centring nut - A large receiver and stop assembly mounted in centre of spider to allow closure of larger spiders and eliminate operators reaching in over spiders .
Clamp - Various types of device used to hold the various parts of a mould tool together during moulding and then allow opening of the mould tool for de-moulding and filling.
Clamping pressure - The pressure required during the moulding operation to keep the mould closed.
Clamshell machine - A rotational moulding machine design where heating and cooling occur in the same place. The doors of the machine are curved and open vertically hence the name.
Closure (Lid) - The sections of a mould tool removed from the section of the tool fixed to the moulding machine to allow the moulding to be removed.
CNC model - A model produced from a 3D CAD file with moulding shrinkage allowance and casting contraction built in. From the model resin patterns are produced which are then used to cast the sections of the mould tool.
CNC mould - A mould produced by directly machining CNC from 3D CAD files aluminium mould plate.
CNC tool path - The programme written to control the CNC machining centre when it cuts the mould tool cavity.
Cooling time (cooling cycle) - the amount of time the mould tool is in the cooling chamber cooling the polymer.
Compound - Polymer that has been mixed (normally to colour it) by extrusion compounding.
Core pin - A pin used to form a depression on the outside of a rotationally moulded part which is an undercut to the way the mould is pulled apart. Core pins are removed before the basic mould is pulled apart. There are two categories of core pins; fixed and removable, the removable pin is usually used per the definition "which is an undercut to the way the mould is pulled apart". It can also be used when its direction is with the direction of mould opening as is the case with fixed pins. Core pins are most often a machined feature.
Cored through hole (through hole) - the area of a moulding resulting from internal protrusions in a mould which, when the mould is assembled, come together to touch creating a tube through the moulding.
Counter balance - Machined weights and mounting system to counteract the weight of the tool(s) and allow the moulding machine to rotate smoothly.
Date code wheel - Machined insert to track moulding day, month, year and shift.
De-moulding - The act of removing parts from a mould.
Drool - Unwanted flow of moulding material on the internal surface of the moulding under the effect of gravity. This is normally caused by rotation being stopped before the material has cooled sufficiently.
Double walled moulding - A part design which contains two walls in close proximity, forming a single-walled structural component. This design may contain kiss-offs or be filled with foam for added stiffness.
Draft (draft angle, draught angle) - A taper designed into the mould. This is normally used to facilitate removal of a moulding from the mould, or to allow a tool to be cast successfully. Draft is normally designed in degrees.
Double-stacked tool (piggy-backed tool) - Arrangement of tools on the machine where one set of tools sits above the other to increase the tool carrying capacity of the machine. The top set of tools is normally removed from the machine to allow the lower set to be de-moulded.
Draw - The direction in which the moulding is removed from the tool, common usage "the feature is in the line of draw".
Drill points (drill pips) - A small protrusion in the mould which leaves an indentation in the moulding used to locate the point of a drill when drilling holes in secondary operations.
Drop arm (offset arm) - A machine arm where the mould mounting plates are 'dropped' and are therefore 'offset' to the centre of the actual spherical operating area of the machine. Normally used to allow larger (but fewer) tools to be fitted to a given size of moulding machine.
Drop box (dump box) - An insulated hopper mounted to the inside or outside of the mould for holding plastic resin or powder that can be released at any time during the moulding cycle to produce a multi-layered moulding wall section.
Dry Flow - Term used to describe the measure of dry powder flow which is important in rotomoulding as it gives a good indication of the way material will flow in actual moulding. The standard method for measuring dry flow is to put a predetermined volume of powder into a standard funnel and measure the time taken for the powder to flow through it.
Dry Mix (Dry blend) - Polymer that has been mixed (normally to colour it) in a mixing machine. The polymer and the pigment are in powder form but the pigment has a much smaller particle size than the polymer.
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