Glossary of industry terms A to B
Air injection - See inert gas injection.
Air ejector - a device which ejects the moulding from the mould tool using compressed air.
Air mover (airflow amplifier) - A device that uses a low volume of high pressure air (fed through the machine arm) to create a high flow of oven temperature air aimed in a specific direction. They are used to heat deep-cored and other hard to reach features in mould tools so that the tool is at a more uniform temperature and therefore the moulding will tend to be of more uniform wall section.
Alignment key - Key mounted to the centre guide pin to align the top and bottom spiders and therefore the individual moulds on the frames.
Alignment pin &bush (dowel pin &bush) - Precision machined male & female parts fitted to the flange of the mould tool to align the sections of the tool one to another.
Anchor Insert - A commonly used insert for moulding-in which is made from either hexagonal or square stock with circular grooves machined to give very good torque and pull out resistance.
Annealing - The heating then gradual cooling of normally metallic components to relax internal stresses. Commonly mould tools and spiders are annealed to maintain consistent dimensions after the heating and cooling process used in rotational moulding and therefore avoid the need to carry out further engineering work after an initial period in production.
Anti static (anti stat) - 1. An additive that works as a processing aid by minimising the build up of static during mixing and moulding.
2. An additive that reduces the build up of static in the moulded product.
Arm - The part of the moulding machine extending out from the central turret of the machine to the point where the tools are fitted.
ARM - The Association of Rotational moulders. A USA based International organisation which represents and supports the industry.
Auto-reverse - a common feature on moulding machines where the machine rotates in one direction for a set period of time, and then reverses direction for a set period of time, and repeats this throughout the moulding cycle to produce a more uniform wall section moulding.
Big Head fastener - A commonly used insert for moulding-in which is made from a welded assembly of a male or female thread to a backing plate of either expanded metal or a custom pressing. Gives very good torque and pull out resistance, and offers a robust thread.
Biaxial rotation - the rotation taking place in the moulding process where the tool is rotated through 360° in two axes which are orientated at 90° to one another.
Blow hole - A void through the wall of a moulding caused by pores or holes in welds, poor insert fit, porosity in aluminium casting, poor mould flange condition, or a blocked or incorrectly sized vent.
Blueing in (matching in, fitting) - A method of matching mould parting lines to obtain a close fit. Engineers' blue is smeared on one part and the other mating part offered to it and then viewed to see the areas of contact.
Bolt, receiver, and stop - This system is designed to quickly clamp and unclamp spiders . The system incorporates stops that prevent over-tightening and potential damage to moulds.
Boss - 1. A protrusion from the surface of a mould used to produce an indentation in a moulding.
2. A protrusion from the surface of a moulding produced by an indentation in the mould surface.
Bulk density - The term used to describe the density of the powdered polymer not the homogeneous polymer density. The figure is much lower at roughly 15%.
Bridging (webbing) - 1. Improper flow of powdered resin in the mould due to resin touching across one wall to another. This condition can be caused by narrow mould passages, poor mould and/or part design, improper rotation, poor powder flow properties, and incorrect resin type.
2. An engineered feature to create a 'bridge' of moulded material from one mould wall to another, most commonly to increase the stiffness of the moulding.
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