Core Staging and Setting Kaizen - Joseph Vitalo

Background

A manufacturer of ductile iron casting products for the automotive industry is engaged in a major rollout of Lean throughout its manufacturing function. As part of this rollout, it is developing a team of Kaizen event leaders. Their training involves classroom instruction and practical experience in doing events.

The company's backbone production system passes through five stages: Core, Mold, Pour, Separate, and Finish. Cores are forms that are set into molds. Molds are used to cast the products. Pouring introduces the molten metal into the molds. Separate extracts the casting from its mold. Finish ensures the product is free of spurs.

The Manufacturing division identified the core staging and setting work process as the focus for the team's first Kaizen event. In staging, cores appropriate to the job being run are assembled and loaded onto carts for transport to the core setting area. The setting process places cores into a mask which holds the cores. A machine (DISA 2070) holds the mask and, once loaded with the required number of cores, it uses the mask to set the cores into the mold.

Core staging and setting throughput constrains the production of molds and that constrains the throughput of the entire production system. Reduced throughput introduces inefficiencies that raise cost and endanger on-time delivery. Industry customers unremittingly demand consistently reduced pricing and timely delivery of products. To remain viable as a supplier, you need to consistently reduce cost so that you can meet pricing demands while sustaining profitability. You also need to supply a consistently high quality product when it is required.

The Kaizen team was made up of the Kaizen event leaders-in-training augmented by an operator who performed the work process. Several of the trainees also worked in and with the target work process. As the event unfolded, input from all process operators was elicited and used to uncover the sources of problems and their fixes. The event was led by the trainee's instructor and applied the Kaizen method documented in the Kaizen Desk Reference Standard. The final results of the event were the cumulative contribution of the team and the work process employees.

Scoping the Event

We prepared for the event by defining a scope and using its information to analyze the likelihood that the event would accomplish its purposes. A scope document defines the focus, boundaries, and expectations for performing a Kaizen event. It includes information about the business within which the work process operates, the target work process itself, and the expectations stakeholders have for what the Kaizen Event should produce. We use the scope document first to inform ourselves about what we are being asked to do and then to align stakeholders with the proposed purposes of the event. It is not uncommon that different stakeholders initially have differing images of what a proposed event will address and deliver. By documenting the answers to these questions in a scope statement, everyone sees the same set of ideas and can raise their concerns and, together, agree on a single, common image.

Issues Encountered in Defining the Scope

As is frequently the case, building the scope uncovered and clarified key issues that would have undermined the event had they not been recognized and addressed. First, the work process we were to Kaizen was not clearly identified. We uncovered this by noting the different language people used to refer to it as we gathered the scope information. This led us to press to see the work process. We learned the major operations associated with the Core production stage. These are core making, core staging, and core setting. Cores are formed in the core making process, and no one had this process included in their thinking about what we would Kaizen. Some stakeholders however did include core staging as part of the stream of work they thought would be included in the event. Most just assumed that the core setting activity itself was the focus. As we evaluated the alternatives, it seemed that the connection between staging and setting was so close that it needed to be included.

Another issue resulted from the process being mixed model and multi-lined. With a mixed model, you either Kaizen the backbone process or you focus on a single model variation of the process. We needed to understand how much of the process varied by model and what focus would leverage the best results for the company. Analyzing that question before the event allowed us to properly assess our alternatives. It also uncovered the need to investigate production scheduling, so we could know when the various models were scheduled for execution. This was key to the team being able to observe the process during the event. These observations occur twice—before and after we make "improvements." The before observations measure waste is the process as it is currently operating and the after observations repeat those measurements thereby allowing us to calibrate improvements. We settled on focusing the event on the most complex model produced as any improvement we generated would have the broadest degree of transfer across all models. We also decided to improve performance on both lines. Since the lines were not identical, we needed to understand before the event how they differed so that we took this into account in performing the event and developing improvements.

A third issue was measurements. Initially, our sources did not have measurements for cycle time, rework, scrap, unit cost, labor component of cost, operating budget or most other metrics we would evaluate. Measurements were focused at a higher level and were not specific to the work process we were to improve. As we explored the issue with various people, we uncovered that there was indeed more measurement information available than people initially thought. We also arranged to augment some missing information by doing selected baseline measurements prior to the event. When we finished our preparations, we had a solid data set to use in the event.

Strawperson Direction

As I said, our first uses of the scope document are to align stakeholders and educate ourselves about what we are to accomplish. The next use is in preparing for the event. We build a mission, goals, and set of do's and don'ts from the scope document so that we can focus our preparation efforts. We call this a "strawperson" direction because it is based on the stakeholder's perspective only. We do gather enough indirect information (worker perspectives, performance data) to be confirm that the strawperson is plausible. However, once we begin the event, we directly observe and measure how the work process is operating and let the facts of the workplace either confirm or adjust the event's mission and goals. Exhibit 1 presents the strawperson direction for the core staging and setting event.

	Exhibit 1. Strawperson Direction for the Core Staging and Setting Kaizen Event
	Mission To increase profits while satisfying customer pricing requirements by improving cycle time, reducing cost, improving ergonomics and safety, and reducing repetitive motion.
	Goals Reduce cycle time Improve throughput by 15 molds per hour on each line Reduce rework Reduce scrap Reduce safety hazards due to ergonomics Increase molds per hour
	Do's and Dont's
	Must Do's	Can't Do's
	Work within union guidelines Work safely Make sure any changes do not adversely affect other work processes	None

The Event

Since all the team members knew each other, we began the meeting by reviewing the mission of the event, its goals, and do's and don'ts. We made sure that everyone was aligned with the purpose we were to serve. Since the team was familiar with our Kaizen process through previous training, we skipped the introduction to Kaizen. We set ground rules for working together, briefly reviewed our Working With Other (WWO) skills, took care of administrative issues, and got to work. The WWO skills emphasize using clarifying and confirming skills to understand each other's ideas and constructive criticism and hitchhiking to build on them collaboratively. We followed the Kaizen process as described in the Kaizen Desk Reference Standard (Exhibit 2).

	Exhibit 2. Kaizen Event

Focus

Our first step was to build a work process description. The Core Staging and Setting work process operated in batch mode with a unit of output being one fully set mask. A mask holds the cores and the mask is used to set the cores into the mold that will be used in casting. For the product model we observed, the mask required eight cores and the production run required 128 masks to be produced.

The process begins with a production schedule that is sent to the Core Setting supervisor. The core setters review the schedule, get the pattern and mask required for the product being produced, and load the mold producing machine with the pattern and mask. Next, the core setters get the cores required for the job and transport them to the machine. For a run of 128 units of the model we observed, this required staging 1,024 cores. The cores sit on metal carts that must be pushed to the machine. A cart can weight up to 1,200 pounds. When they arrive at the machine, the carts must be oriented correctly to allow the core setter to rapid get cores from the cart for placement on the mask. This requires much pushing, pulling, and twisting to properly position the carts. Once the cores are staged, the core setter must prepare the computer that drives the mold making machine. He or she enters the job card information (e.g., part number, production quantity, pressure settings) needed for the computer to manage the machine's operation. Once the computer is setup, the core setting operation begins. Up to two people will work in tandem to set cores on a mask. Once the mask has its compliment of cores, a button is pressed and the machine proceeds to set the cores into a mold. When it returns, it presents a the mask empty of cores and the setting processed is repeated.

To complete our map, we gathered critical information about each operation in the process (for cycle time, location, contact person, documents).

Walk Through

The walk through was an eye opener in several ways. First, the rapidity of the work and enormous amount of movement told us we needed to videotape the process and do our measurements off the videotape, as we could not record fast enough to properly capture the core setters' operations. Second, we saw the core setters waiting, not the production line waiting for the core setters. That told us that we would need to observe machine operations, not just human operations, if we were to improve throughput. Third, we learned from the operators that they periodically had to shut down jobs because the masks were not holding the cores they set into them. This created serious rework and delay. Fourth, we observed forms of waste that were not addressed by the current goals for the event, but needed to be if we were to accomplish our mission. We also did our interviews of the work process performers and benefited from their thoughts about how to improve the process.

Final Mission, Goals, and Do's and Don'ts

As it turned out, the facts on the floor confirmed the mission for the event, but caused us to modify the event's goals. First, we could not observe rework itself as the rework caused by problems in the a current run are addressed in future runs. We felt we could address rework by correcting machine-related problems (masks dropping cores and other issues). Next, there was no method used to track scrap with this work process. We could see containers with core scrap in them, but whether the scrap was a result of the work process we were observing or just discovered during the work process was beyond our ability to resolve within the event. (We did reduce scrap—cores, molds, and metal, but we could only precisely measure the reduction in metal scrap within the event.) Based on our walk through, we added several new goals that attacked waste key to our mission, but not identified by the stakeholders as an issue in the scope document. We were also able to generate quantitative targets for waste reduction. Exhibit 3 presents our final statement of mission, goals, and do's and don'ts for the event.

	Exhibit 3. Final Direction for the Core Staging and Setting Kaizen Event
	Mission To increase profits while satisfying customer pricing requirements by improving cycle time, reducing cost, improving ergonomics and safety, and reducing repetitive motion.
	Goals Reduce cycle time Improve throughput by 30 molds per hour across the two production lines Reduce motion by 30% Reduce rework 10% Reduce scrap by 15% Reduce safety hazards due to ergonomics by 100% Reduce setup by 25% Reduce travel/transport by 50% Reduce wait by 35%
	Do's and Dont's
	Must Do's	Can't Do's
	Work within union guidelines Work safely Make sure any changes do not adversely affect other work processes	None

Evaluate

Using our insight from the walk through, we videotaped the work process and made our process observations from it. We also observed machine operations and investigated the source of the problem with masks dropping cores. Finally, we did not see the cause of the wait states in human operation, so we searched downstream in the value stream to locate where the bottleneck was occurring. Exhibit 4 presents the highlights of the evaluations findings.

Human Operations

The major forms of waste detected with respect to human operation was wait (47% of cycle time), setup (21%), travel/transport (10%), and motion (8%). In addition 15 examples of hazards were detected, mostly ergonomic in nature. Wait was due to machine operations. We observed no rework during the process observations of worker performance and eliminated the rework reduction goal as a consequence.

Machine Operations

To understand what we found with regard to machine operations, we need to take a closer look at the machines. There are two machines operating in the core setting area (mold making machine and the Sand Dam) and a set of two collaborating machines operating in the pouring area that we ended up investigating.

The mold making machine was described above. As it executes its operations, it must hold fast the pattern and mask mounted on it. The pattern is used to produce the molds and the mask holds the cores that are set into each mold. If either part comes loose, it will result in a defective mold and, if not caught, a defective casting. after a good deal of investigating that required interviewing operators and maintenance pattern shop personnel, and evaluating stoppage reports, we discovered that the mounting pins for these parts was insufficient to maintain a tight fit throughout a run. This was one major source of rework and scrap.

The Sand Dam deposits a fixed amount of sand in a line that separates the pour hole in one mold from the hole in another. As the cores proceed they are packed together one after another. To ensure that no excess metal from the pour into one mold spills to the following mold, a line of sand is placed to "dam off" each successive pour hole. The Sand Dam machine must place this line of sand in the correct location and not allow any sand to spill into the pour holes. In fact, it was spilling sand into pour holes and that was causing defective castings that ended up being scrapped. The problem we observed was that the machine was dropping sand too late. The operators can adjust the machine, but the bolts used to tighten down the adjustment were not holding. The bolts were plastic and would strip and the operators were innovating methods to reinforce the grip of the bolts. Their solutions were not working.

Solve/Act

The team generated 53 improvement actions, which collectively addressed every form of waste it detected. Twenty-three (23) actions were prioritized for implementation during the event. The remaining were assigned for implementation after the event. Here are some highlights.

On the human side, the team modified the scheduling of job runs to group jobs using like metals, designed a new plastic dunnage system that would greatly reduce ergonomic issues and setup, 6S'd the work area to reduce travel and transport and eliminate hazards, and introduced cross training for production control personnel, among many other actions.

One of the simplest improvements introduced a small scrap box for damaged cores placed at the mold making machine. Previously, the box was across an aisle and required the worker to either hurl or carry an 11 lb. core 25 feet to the bin. Another introduced better shielding from sparks in several work and walkway areas. The new dunnage system required the most detailed planning. A subteam conceptualized the solution, research alternatives, and described a new system for stacking, transporting, and orienting cores. The new system uses plastic pallets and carts, and greatly reduces the weight of the carts and the need for turning and bending by the operator. One of the most significant improvements changed the scheduling of work. It sequence jobs based on the metal used in casting. This reduced setup dramatically and wastage.

On the machine side, improvements modified maintenance methods, recalibrated software controls, and modified machine parts to extend their mean time to breakdown. Preventive maintenance procedures were rewritten and rescheduled for daily implementation. The software controls for the pouring process was re-calibrated to cycle at a 15 second rate, as opposed to the off-spec 30 second rate. The plastic bolts for holding masks and patterns were replaced with metal one's that did not strip and cause the components to slip and damage cores and molds. The Sand Dam lock bolts that ensured proper placement of sand were also replaced with one's that held.

All these changes were only possible given a team of motivated and skilled workers who could engage their fellow workers in the process of uncovering opportunities and conceiving improvements. The range of improvements made was only possible with the help of all workers associated with the core staging and setting process and the downstream pouring process. The team actively involved both line and support staff including people working in the process controls, engineering, maintenance, and safety departments.

Close-out

Results

Before we complete an event, we measure the effects of our improvement efforts (see Exhibit 5). The post improvement process observation revealed that cycle time was reduced by 29% and process's value-added ratio was improved by 71%. Wait was reduced by 61%, travel/transport by 85%, setup by 29%, and unnecessary processing by 58%. Scrap was reduced 21.66 tons per month and throughput was improved 88%. Eight (8) of the 15 hazards were eliminated in the event. The remaining hazards are scheduled for elimination as a follow up to the event. The annual monetary benefits produced by these improvements exceeded $180,000. The team devised a set of leave-behind measures that it posted in the workplace so everyone could track the sustainment of the improvements made in the event. It also generated a number of insights from the event. Two key ones are:

• Observation is critical to discovering what is actually happening. The team discovered that the operators were not the bottleneck at all; it was the machines. Also, the rework and scrap we observed were due to machine operations, not human operations.
• Process observations of rapidly performed work operations are best done from videotape. We observed over 900 human operations performed inside 45 minutes. We taped the observations and did our measurements using the tapes. We could never have recorded the observations in real time.

	Exhibit 5. Summary of Results
	Cycle time reduced 29% Value-added ratio improved 71% Throughput increased by 88%  (29 molds across the two lines) Travel/transport reduced 85% in cycle time and 76% in distance (from 1,907 feet to 458 feet) Wait reduced by 61% 8 of 15 hazards removed (follow up actions will remove remaining items) Set up time reduced by 29% Unnecessary processing reduced by 58% Scrap reduced by 22% Over $180,000 in net annual savings

Stakeholder Close-out Meeting

The close-out meeting brings together the key stakeholders and all persons affected by the event. The key stakeholder get to see how the event turned out and match its results to their expectations. All the affected parties have yet another opportunity to comment on the improvements, discuss the issue of sustaining them, and comment on the additional improvements the team recommends for post-event implementation. It is a key component of keeping everyone connected to the change efforts and cementing their alignment and support with the overall Lean initiative. The team led the close-out. Stakeholders were openly amazed by the range of opportunities uncovered by the team and the range of improvements it developed. Participants hitchhiked on the information and ideas the team reported suggesting savings the team had not recognized and ways to transfer improvements elsewhere in the workplace.

Published November 2005

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