Page 85 - MODULE QUALITY TOOLS DMQ 30262

DMQ 30262

CONTROL

In the Control phase, the implemented changes based upon the Six Sigma
methodology are continued and monitored. Once improvement opportunities have been
implemented, by continuing to measure the process, using SPC, (statistical process control),

to trace and confirm the stability of the implemented improvements and the expected results
in the process.

Sometimes but not always will include some process management methodology

including process ownership. A statistical theory that can indicate whether a process
operating within an acceptable range and if it is being influenced by variations mainly
attributed to "common cause" factors. Any processes that can operate in this condition are

said to be "in control".

Injection molding machines are widely used in industrial applications. The velocity of
injection process and the pressure of dwelling process must be controlled with all products;

however, such control is very difficult. In fact, the tuning of the controller parameters needed
for high quality or multi-objective production takes a long time and requires a high level skill
from the professional field engineer.

To prevent incomplete filling or flashing, the mold, the shot-to-shot accuracy is a
critical factor. It is also important that multifamily molds are well balanced. Hot runner

manifold also be must balanced and the number and size of drops must be sufficient for low
pressure mold filling. Mold temperature is an important factor too. Accurate control of the
temperature is important when running molds with core lifters for the multiple shots

The various parts of the mold also must come together precisely. If they do not, small

leakages will occur. When this occurs, it is referred to as flash. To prevent flash from
occurring, which can cause damage to the mold, technicians slowly increase the pressure
used in new molds until they determine the proper amount of pressure to get the desired

results. Other factors, such as temperature, venting, and resin moisture, can also cause
flash to occur

The melt temperature is a critical process variable affecting directly the final quality of

the molded parts. The control of this variable is difficult as the dynamics of the resin melting
process are known to be nonlinear and varying in relation to the barrel heating power. In this
paper, we present the development of an adaptive generalized predictive controller (GPC)

which is suitable for the control of the melt temperature. Unlike previously reported
KKTM Kuantan 84 DMQ 30262