For producing the plastic caps, the injection molding system is the traditional way and Smargon Plastic just worked with this system in the past years while we are already seeking the better solution for our customers. In 2011, Smargon launch the brandnew product, SMCM (Smargon cap compression molding system) for plastic closures, a new alternative solution for our customers who need to produce the caps. Controlled by Siemens PLC, actions carried out by the Omron frequency convertors, YUKEN hydraulic rotary compression system & hydraulic mold open/close system, the special designed extruder with efficiency heating unit, plus our huge experience in the caps’ injection molding & concern on closures development and testing ensures extremely high level of this new product suitability. In one words, SMCM cap compression molding system can offer you an advantage within the compression in terms of lower production costs and product better quality. 
 

System Overview

Comparing with the plastic cap injection molding machine, the plastic cap compression molding machine works in a very different process while in a simple process in the working process. Two units in Smargon cap compression molding machine: Extrusion & plasticization unit and compression molding unit. Through the extrusion &plasticization unit, the regular melten plastic resin will be put into the cavities, the mold close to form the cap, cooling, ejecting, the whole process just finish. 

Working principle
In a short word, Smargon plastic cap compression molding machine works as simple process: A precisely measured drop of resin, cut from a continuous extruded stream, is placed into a transfer wheel. The same wheel also takes finished caps out of the main wheel.

Position 1: The transfer wheel comes to a position above on empty cavity of the main wheel and drops the plastic into it.
Position 2: The cavity lifts vertically up into the core and the actual molding takes place.
Position 3: The plastic now spreads between core and cavity, climbing up the cap side walls under relatively low pressure. It therefore leaves no sprue point, which bring a great advantage for the caps whose surface need decorating.
Position 4: The fully formed cap is now cooling.
Position 5: The cavity moves down leaving the cap on the core. The core parts will have continuous actions to separate the cap tamper brand from the bush, and separate the cap’s thread parts (the main cap body) from inner core. Finally, with the help of low pressure compressed air, the cap will separate from the core part completely. 

 

Injection Molding -Compression Molding
The main differences between the two methods stem from the fact that the entire cap injection mold in the injection molding system has to move opne/close for each cycle where in cap compression system only individual cores move. This and other differences make plastic cap compression molding more energy efficient: Less parts is moving for the production of each cap
Material temperatures are lower (220-240 in injection molding, 160-180 in compression molding)
A continuously running turret requires less energy than the discontinuous operation of an injection molding machine Compression pressure is lower than injection pressure.
At the same time, in the cap compression system, it also does not need sophisticated systems to centre two mould halves but instead relies on relatively simple guide bushings, which reduce the difficulty for system operation. The whole system structure is a simple one with an easy maintenance design base. Only extrusion & plasticization unit and compression unit to be the main machine, less space required, convenience for maintenance. In additional, because it does not need the plates and complex hot runner systems used in injection moulds, the cap compression tools are generally less expensive, especially when the capital cost is compared to the output per year, which makes the mold change be easy consideration when producing the different caps. Thus, there are many advantages selecting the Smargon cap compression molding machine comparing with injection molding. 

Great Repeatability
The compression process is characterized by a smaller amount of unknown factors like these happened in the injection molding process, plasticization temperature, injection pressure, injection stroke, mold open/close, cooling, and all the related parameter setting need to be set by the skilled engineer to startup, which helps you can getting more consistent results from compression process: the deviation from the required quality standards of plastic is very small, which guarantees a consistent product repeatability. 
 

Technical Drawing