Optimising time cycle and machine productive time Whatever ideas for cost saving are introduced into the injection moulding of plastic components，ultimately the time cycle of the machine and the rate at which it can be made to produce good saleable…
Fixed and variable costs The main fixed cost of the injection moulding process is，of course，the capital cost of the equipment, but other fixed costs—rent of property，rates，etc.— must not be lost sight of. In the world of the entrepreneur—and such people…
Injection moulding process variables and their causes [one_half]Variable [/one_half][one_half_last]Possible cause [/one_half_last] [divider_line] [one_half]Injection pressure [ Dirty oil; blocked filter 2. Faulty pump; cavitation 3. Faulty relief valve 4. Overheated or cold oil [/one_half_last] [one_half]Injection rate [ Overheated oil 2. Air,…
Sink marks and voids Sink marks and voids are two manifestations of the same fault, and their complete eradication is extremely difficult. Diagnosis is easy. All plastics take up more volume when molten than when solid，and where there is more…
Undercuts An undercut is a part of the mould where the molten plastic flows behind a retaining section thereby preventing the hardened plastic moulding from being easily ejected. Undercuts, in general, require moulds with moving parts to allow the product…
Internal stress and warping When thick sections are moulded，rapid changes in temperature can cause thermally induced stresses due to differential expansion. If surface layers cool faster than the interior through poor conduction, the contraction of the surface will be greater…
Sinking The moulding of thermoplastics in thick sections presents other shrinkage problems, especially where mould shrinkage is high (e.g. highly crystalline materials). In a thick section of an injection moulded product，for example, the outside layers in contact with the cold…
Effects and Influence of Mould Design upon Maintenance It is an unquestioned truism that mould maintenance, in reality, originates in the design department when the core features of the mould mechanism are worked out.Moreover, they, in turn, are reflected in the manner…
The correct kind of maintenance for plastic moulds is one which certainly involves much more than is embraced in the all-too-customary practice of a merely perfunctory examination of the tool upon its removal from the production stage, with the almost…
Every mould user has to undertake some kind of maintenance activity.Since faults and damage to the complex mechanism of these tools inevitably occurs even when the greatest care is taken. However, as already hinted, experience reveals such activities to consist…