The mould impression Often incorrectly referred to by some engineers as the cavity，the mould impression is a hollow area contained inside the mould into which molten polymer is injected and allowed to cool. When a mould tool contains more than…
How to identify Faults in injection molding A logical and systematic method of dealing with faults is most desirable, and many practical moulders have their own scheme of operation. In compiling such a scheme, it is important to ensure that…
Injection molding allows mass production of precision plastic parts once the initial molds are made. But successfully navigating this intricate process requires understanding its nuances. This 10-step guide breaks complex mold design into simple, logical stages for flawless execution. 1.…
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…