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Kaizen Event Case Study   

NC Machining 

Event For NC Machining

How a Kaizen Event helped a jobbing-type machine shop implement workcells and set the stage for dramatic improvements in inventory, delivery, productivity and quality.

Background

* Note: While there is little that is proprietary about pumps, the controls and mounting of FDC's pumps are highly specialized. Only a few manufacturers in the U.S. build them. For this reason, we cannot reveal the client's real name.
Fluid Dynamics Corporation (FDC)* manufactures specialized pumps. Most of them are quite large. To support this, FDC has a machine shop with about 75 employees and 125 machines. Roughly half of the equipment has modern CNC. About 2100 parts are active.

Preparation

FDC's product-process mix was far too complex for informal analysis and grouping of parts into cells. Several months were required for a Production Flow Analysis to develop part families.

With the part families and their respective cells defined, we then designed a Macro- Layout showing the location of each workcell. The detail layout of the cells was to be the responsibility of the Kaizen teams.

A simple cell was chosen for the first Kaizen effort. It consisted of two nearly identical large Horizontal Machining Centers (HMC). The part family had about 15 parts and these were further subdivided between the HMCs. This helped to reduce fixture changes between the machines but allowed any part to be made on either machine in case of emergency.

The Event

The team consisted of cell operators from two shifts, engineers, and maintenance personnel. The team analyzed the process, identified opportunities and made improvements.

Initially, problems were identified in the following areas:

  • Parts were moved to other departments for washing and deburring.

  • Fixtures had design defects.

  • Scheduling often required parts that were unneeded while needed parts were short.

With some investigation, the team determined that washing and deburring of the parts was easy and required little time. It was suggested that these operations be brought into the cell and performed by the operators internal to the 20-minute machine cycle. 

This brought on protests from the machinists. Further investigation revealed why the machinists did not like this idea. It seems that most of their internal time was occupied measuring dimensions from the previous part and recording these dimensions on a three-page QA form. Further discussion revealed that all but one of these dimensions was machine controlled and always within tolerance.

As a result, the QA forms were greatly simplified thus allowing time for the machinists to wash and deburr. With some experimentation, it was found that the deburring and most washing could take place without removing the parts from the fixtures and this further streamlined work within the cell.

A simple Kanban system was designed that allowed the machinists to schedule their own operations with strong communications with the assembly line.

Engineering modified the fixtures and the operators made programming changes which further improved machine productivity.

Results

In the three months after cell startup, the pump assembly line was never once stopped or inconvenienced by a parts shortage from this cell.

WIP inventory went from three months to three days. Productivity improved by about 50%. Capacity was released for increased production demand. Quality improved even with the abbreviated inspections.

HMC Workcell after Kaizen event

Horizontal Machining Cell Detail

Note that the layout is nothing special. The HBMs have not even been moved. The success of this cell depends primarily on the way it operates, work balance, quality and the Kanban system.

Plant Layout-Cellular Manufacturing

Macro-Layout

This macro layout shows the position of each workcell. Machining workcells are designed around families of similar parts. the Horizontal Machining Cell (above) is near the center of the layout and adjacent to the assembly area.

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