Continuous Improvements, Cost Savings at McConway & Torley
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McConway & Torley LLC (Pittsburgh) is as old as the American railroad industry itself.
The facility in Pittsburgh has an expansive history, one of more than 130 years. This plant began rebuilding in the late 1970s. Modernization occurred on a yearly basis. Investments to address some of the critical issues in coremaking and molding practices were added on the budget and now, things are moving fast.
Generally, the older the company, the larger the extent of improvement needed. The first challenge is updating the technology. Following closely behind is having a skillful workforce. In terms of technology adoption, metalcasting facilities are perhaps the slowest of all the industries, partly attributed to the demand from the markets that buy its products. As a railroad facility, McConway & Torley tends to react to the same production pace and quality requirement specified by the governing organization, such as changes to the allowable centerline shrinkage or chemistry requirements.
That being said, when a product does not change in years, there are some hidden advantages:
1. Pouring a single grade of steel is less problematic.
2. Fewer heat treat recipes and more consistency in the process is achieved, giving the flexibility of implementing new practices, say, in the molding or pattern shop.
3. Small variations are easily noticeable in the cleaning room.
4. The plant has better control over scrap and revert utilization.
On the other hand, when a product/process does not change in years, disadvantages abound:
1. The mindset of the employees becomes stagnant unless new technology comes along.
2. Treating training programs in an “out of sight, out of mind” manner with no real dedication of time and attention to the problems is not the answer in the face of changing technology and adversity.
3. Rapid employee turnaround into different departments, leads to assumptions on the learning curve of an employee.
4. Cosmetic touch-up to parts are given more importance than real soundness of the casting.
5. A barrier to communication/cooperation exists due to a false sense of product knowledge.
Notable Improvements and Results
Prior to implementing continuous improvement projects in the heat treat area, the heating rates were not being controlled accurately (Fig. 1). As a consequence of this uncontrolled heating rate, temperature uniformity across different sections of the casting was compromised. For the section thickness size of the parts that McConway & Torley currently produces, this rate would mean the center sections would not achieve the temperature that the outside sections would as quickly, resulting in quench cracks. This effect is even more pronounced in winter months.
To overcome this problem, the heat treat cycles were modified in such a way that there is now two soaking times, shown in Figure 2, before subsequent quenching operation. The first holding cycle ensures the thick section also attains the same temperature as the outside before the second heating cycle.
Some castings that McConway & Torley produces in large quantities require a smooth contoured surface that will be gaged prior to being sent to a customer. These castings used to be made traditionally by incorporating a cored surface which creates that smooth contour. In addition, there was a riser on the top of the core. Trials were performed to mold that contour in green sand with limited success. However, with the addition of a custom made riser which fits that contour and the combination of good green sand, the plant was able to eliminate the core altogether. These changes resulted in an increase in general green sand quality, coupled with a decrease in time spent grinding the casting for gauging requirements. Figure 3 shows the difference between the cored surface, on the left, and the green sand surface, on the right.
One of the dilemmas a continuous improvement engineer must face when changing an already established process is to prove that the new process would be substantially more cost effective than the old one. In the course of achieving this objective, McConway & Torley set out to change a product which was the highest production piece at the company and had remained unchanged for more than 20 years. It was a daunting task.
The problem that was most evident when McConway & Torley first took up this project was excess grinding. The other driving force to change this part was improving the surface quality by at least twofold. In addition, the melt department was finding it difficult to pour these castings due to off-centered pouring cups. Figure 4 shows general surface quality that was achieved prior to making this improvement and the difficulty the melt department had to endure in pouring these castings. Traditionally, the melt department had to pour these castings in an alternating technique. This created problems in positioning the crane above the cups. More superheat and thus more energy was needed to pour these molds. They turned to a new practice of pouring all straight lined pouring cups and came back and poured all the cross pouring cups. However, two molds are in a flask and all the gases that were generated when they poured the first pouring cup accumulated in the second half of the mold. Occasionally, metal would run over to the other side of the mold. In order to eliminate these problems, the gating design was taken back to the drawing board and the traditional way of gating the casting was changed.
Research has been done in the past regarding the size of the riser’s breaker core in relation to the section size the riser would feed. On a particular casting that was using a 50% breaker, the operators had spongy shrink piping into the casting from the riser. This required extra welding on the casting surface and subsequent heat treatment due to the weld. Using a 70% breaker eliminated these problems by breaking clean and ensuring a solid casting (Figs 5-6).
Another instance of improving yield on a group of castings is decreasing the required risers from four to just two, shown in Figure 7. By following each step of the process and taking into account all customer solidity requirements, this objective was achieved. This small step translated into a big change for four separate castings. This eliminated the need to air arc the riser and was the first step toward tighter cost control evaluation and a savings program that the company is implementing today.
A major drawback an older facility suffers from is the foresight of a proper material movement. This could be due to two major factors. One is older layouts which were not accommodating for future equipment installations. The second is a change in the product line. Accommodations due to the changing product line can be addressed without much difficulty. The real bottleneck however is the layout. The travel path of the forklifts was haphazard around the cleaning room for different products. A new ideal configuration was designed for a more logical flow of every part and parts were kept separate.
Substantial cost savings can be achieved by a proper work culture where all departments work towards a common objective. Rigging changes were made wherever necessary to eliminate extra grinding and heat treating following weld repair. This was also beneficial in freeing up storage space to put other necessary foundry supplies. Segregation and piping under the riser was eliminated by increasing the breaker opening from 50% to 70%.
Depending on the positive takeaways of the projects implemented at McConway & Torley LLC, the scope of improvement lies in the below areas:
1. Benchmarking with others in the industry—It is important to know where a company stands. This may involve a non-disclosure agreement of some sort, but it also would be important to capitalize on the latest processes used by a competitor without hurting competitiveness in any way. Having training programs and roundtable discussions are effective means to discover new techniques outside of the company.
2. Kaizen Programs—McConway and Torley is currently implementing Kaizen/MDI programs. This would result in more feedback from different areas of the plant, increasing the scope of improvement.
3. Rowing in the same direction—One critical element that is missing in many organizations is getting everyone working with the same strategy and towards the same objectives. While devising a strategy, everyone should work in the same direction and communicate the percent completion of a task at certain intervals.
This article is based on a paper presented at the 2015 National T&O Conference. It is being used with permission from the Steel Founders’ Society of America.