MPI, a worldwide leader in wax room and ceramic core injection, assembly and automation equipment, recently presented a paper on the advantages of high-quality process control and automation in the wax room at the International Seminar on Investment Casting in Taichung, Taiwan.
Chris Boylan, Director of Sales and Marketing for MPI, discussed that even though Investment Casting has been around for more than 5,000 years, the industry still struggles to consistently produce repeatable, high-quality, defect-free wax patterns. MPI has customers in 47 countries ranging from the most advanced single crystal airfoil blade casters to the most basic commercial foundries. Yet one thing is universally true: human-controlled processes vary. Variations occur person to person, day to day, shift to shift and hour to hour. These variations compound and invariably leads to variations in all downstream operations through the entire foundry.
Foundries are under pressure to decrease scrap, reduce cycle times, increase throughput, reduce labor costs and maximize casting yields, which is why process engineers have spent so much time and energy attempting to engineer out as much variation as possible in manually controlled injection processes. Further complicating the situation, foundry margins are getting smaller while part geometries are getting more complex.
There are many variables in every process - from the wax itself, to wax temperature, die temperature, wax flow rate and wax pressure. Currently, the majority of wax injectors around the world are manually controlled systems, meaning there is one pressure and one flow rate. This might work well for simple geometries if the process is in control and stays in control. However, once the operator starts making scrap, he independently changes the process. There is typically no documentation, and therefore isn’t repeatable. Most foundries also have dies that can only run on specific machines, even though the injection controls are exactly the same. This slows down production levels and creates a substantial amount of rework on patterns.
Advanced, digitally controlled systems, like MPI’s Smart Systems allow for a more detailed analysis of the process and allow critical parameters to be consistently met. For example, only smart, digitally controlled systems can achieve a consistent, repeatable die temperature resulting in repeatable pattern quality. Flow rate is another critical factor in producing a good pattern. Smart systems can not only monitor in real time the flow rate at the nozzle, it can display and control flow rate as well. Furthermore, MPI’s digitally controlled process allows the system to alarm and notify the operator if flow rate is out of tolerance, and inhibit further injections until the proper flow rate is achieved. With MPI’s Smart Controls, process control lives in the machine… not the operator. You simply create a baseline injection that produces a perfect part every time — something that could never be achieved in a manually controlled injection process.
If you are injecting around inserts or delicate cores, only digitally controlled systems can achieve the variable flows and pressures within an injection cycle required to produce good injections.
The bottom line — MPI Smart Controls can dramatically reduce your injection cycle times and scrap rates, while increasing throughput and casting yields. All systems will produce the same results, so you can load balance your work by knowing that any die can run on any machine. It’s the only proven way to consistently produce repeatable, high-quality, defect-free wax patterns.