The Doctor is notorious for showing up and participating in Kaizen events at his customers’ plants. These events are the most dynamic learning tool available to the heat-treat industry and involve everyone within an organization, from management, engineering, quality and metallurgy to supervision, maintenance, heat-treat operators and helpers. It is a learning tool of incredible effectiveness. Let’s learn more.

 

Why a Kaizen event?

The goal of a Kaizen event is to hold a focused, short-duration, task-oriented activity in which everyone involved is “hands on.”  Nowhere is this more effective than in the heat-treat shop, where the success of the overall manufacturing operation is so dependent on the health of the equipment and processes being run. One piece of equipment or process is normally selected, with the intent of either optimizing its performance or streamlining its functionality so that setups, work flow and processes run efficiently.

Kaizen events are usually three to five days of intense activity where the only job of those participating is to accomplish the task at hand. The following activities are typical:

  • Defining the problem/goal
    (Why are we doing this?)
  • Documenting the current state
    (Where are we?)
  • Brainstorming and developing a future state
    (Where would we like to be?)
  • Implementation
    (How do we accomplish the goal?)
  • Training
    (How do we get better at what we do?)
  • Developing a follow-up plan
    (How do we sustain our success moving forward?)
  • Presenting results
    (What have we learned?)
  • Celebrating successes
    (What’s next for us to learn or do?)

Kaizen events are one of the best ways of accomplishing lean manufacturing, improving the overall operation and promoting morale amongst employees. It is critically important, however, to understand the types of problems for which Kaizen events should and should not be used. With proper planning, Kaizen events can bring breakthrough improvement to an organization.

 

Blueprint for Success

A Kaizen event was performed on one of five integral-quench furnaces in a captive heat-treat shop. The intent was to do a thorough inspection, cleaning, repair and modification (as necessary) of the furnace as a model to implement changes on the other units. The oldest furnace in the line was selected. The goal was to establish a continuous-improvement plan (Fig. 1), including a preventive-maintenance schedule, critical spares management, predictive tool use, TPM and 5S, OEE[2] and review safety/lockout-tagout-tryout procedures, and conduct training. 

The work involved looking into the history of the furnace, major disassembly and cleaning, which included draining the quench tank and shoveling out the sludge accumulation from the bottom of the tank, as well as evaluating all of the components on the equipment. A number of items were uncovered (Table 1), including an analysis of the current nitrogen/methanol system versus a potentially new endothermic-gas atmosphere generator (Fig. 2). This convinced management to purchase a gas generator.

Kaizen Event Action Item List

Another example of a Kaizen event involved looking at TPM (total productive maintenance) in a single-chamber vacuum furnace. The drivers were that cycle times were being extended, minor cycle interruptions occurred too often, temporary repairs were being done, major breakdowns were occurring at a higher-than-normal frequency, the quality results weren’t as repeatable as expected, and no one had quantified these losses. The work focused on avoiding “the seven wastes,” namely transportation, inventory, motion, waiting, over-processing, over-production and defects (remember Tim Wood). 

The goal of the exercise was to achieve:

  • Safety improvements in equipment operation and working environment
  • Reliability of equipment for material conversion, customer satisfaction and lean manufacturing/reduction in WIP inventory
  • Preservation of precious capital assets
  • Prerequisite to smaller lot sizes and inventory reduction

To accomplish the work effort, the vacuum furnace was disassembled (hot zone removed and vacuum pumps dismantled), cleaned and reassembled. One of the major issues that was uncovered included the design of the front door seal, which was contributing to part discoloration and hot-zone (graphite insulation) deterioration. It was discovered that the door-seal design had been discontinued by the manufacturer, and a retrofit was available. The extent and impact of part contamination (detrimental to the pumping system) was another major finding, and better, more efficient cleaning and more frequent pump maintenance was implemented. 

A pleasant surprise during the work was the condition of the internal heat exchanger, shell and internal cooling fan, which confirmed the proper operation of the water system and robustness of the design to avoid contamination even though dirty work was being introduced.  

 

Heat-Treat Training

Training at a Kaizen event is often spontaneous and done “as needed, where needed” typically on the shop floor in one-on-one situations and then summarized when the group gathers to discuss the progress being made. Informal lunch-and-learn sessions are extremely effective with topics either planned or arising from the work being performed. Reference the web version of this column for detailed outlines of atmosphere and vacuum heat-treating training programs.

 

Summary

Kaizen events in the heat-treat shop bring greater understanding of the challenges that heat treaters face in their day-to-day activities and create a can-do attitude when it comes to problems. Actively participating gives management a greater appreciation for and understanding of our needs and what they can do to help. It is a win-win situation for all involved. Schedule one today! 

 

References

  1. Herring, Daniel H., Atmosphere Heat Treatment, Volume I, BNP Media, 2014
  2. Herring, Daniel H., Atmosphere Heat Treatment, Volume II, BNP Media, 2014

Online Portion

Atmosphere Heat Treating

A.    Materials and their heat treatment

  1. Material properties and response to heat treatment
  2. Material certification sheets – What they tell us
  3. Hardness and hardenability 
  4. Transformation diagrams (phase and cooling transformations) – How to use and how to interpret them

B.    Furnace specifics (e.g., integral-quench furnaces) 

  1. Design and construction
  2. Operational and maintenance considerations
  3. Temperature and atmosphere uniformity issues
  4. Furnace atmosphere/atmosphere control
  5. Carbon-potential control strategies
  6. Gas reactions

C.    Quenching

  1. Understanding oil quenching
  2. Managing distortion
  3. Common pitfalls and their solutions

D.    Endothermic-gas generators

  1. Design and construction
  2. Operational and maintenance considerations

E.    Maintenance

  1. Frequency, type
  2. Planned preventive-maintenance program implementation

F.    Safety

G.    Common pitfalls and their solutions

H.    Open discussion – Questions and answers

I.    Summary – What have we learned?

 

Vacuum Heat Treating 

A.    Products being run

  1. Application, size, weight, productivity requirements, geometry
  2. Loading, fixturing, constraints to the system

B.    Materials and their heat treatment

  1. Heating and cooling-rate considerations 
  2. Surface reactions in vacuum
  3. Microstructure and grain-size control

C.    Furnace specifics (e.g., horizontal vacuum furnaces)

  1. Design and construction
  2. Vacuum materials used and their response to heat treatment

D.    Quenching

  1. Understanding gas or oil quenching
  2. Managing distortion

E.    Maintenance

  1. Operational and maintenance considerations
  2. Hot zones
  3. Heating elements
  4. Vacuum pumps
  5. Cooling fans
  6. Water systems
  7. Temperature uniformity
  8. Vacuum and partial-pressure control

F.    Safety

G.   Common pitfalls and their solutions

H.   Open discussion – Questions and answers

I.     Summary – What have we learned?