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Dealing with tools, we often think of them as solutions to specific problems. For example, Single Minute Exchange of Dies (SMED) is understood as a tool to reduce changeover time and gain benefits such us increased capacity and flexibility. In this case however, SMED was used to achieve a breakthrough in quality performance.
A wire manufacturing company in its journey towards “ZERO defect” was dealing with the problem of “loose wire”. The product was a bunch of wires twisted to form a cable. Every time a roll of wire ended, a new roll had to be joined in its place for a continuous length bunch. These joints, if left unclean or knotty, posed a problem in customer equipment at time of processing. The process included a step called rewinding where the entire bunch was wound backwards to check for any protruding wires or knots and repaired. In effect, the company was indulging in 100% inspection. Still there were customer complaints of loose wire. The team had assessed this to be 5%. Some customers were threatening to withdraw the business.
The first step was for the team to realize that rewind was not the value added step and the quality was to be controlled at source- i.e. at the time of joining the wires. When enquired about the alternate ways joining the wire, the team revealed that they already had a cold welding machine but did not use it as it meant keeping the machine down for 3-5 hrs depending on no. of wires to be joined. The team had resorted to slowing the machine down to tie a knot every time a wire spool ended that would be later cut during the rewinding operation. Welding was done only in very few cases when they had low production. With this new understanding, the current Level of Defect was estimated at 95% and a target of 1% was set.
Shop floor study was conducted on current state and analysis revealed that currently on an average every changeover is leading to 180 Mins (3 Hrs.) machine down Time for bunching a set of 30 Wire. The team concluded that given the volumes, 100% welding can be done only if the lost time per changeover is less than 20 min. SMED was selected as a Tool to achieve this and a target of 18min was set by the team (10x Improvement).
Shop Floor video was captured followed by Activities classification related to Adjustment, Loading, Setting and NVA. Individual Activities defined as External / Internal. Being the process was having repetitive nature of Active in One Set Up itself, so study was done for one set of wire jointing from start to end.
Process team participated in generation of solutions. Many Solutions like Increase in height of Welding Machine, Machine ON-Off Switch provision thru Foot Pedal, Welding Configuration were generated by Process Operators.
Considering the repetitive nature of activities, one of the recommendations generated was to have all the Input Reels of Standardized Qty. This helped to minimize the Waste, Loading and Adjustment related Activities in Significant Manner.
After 3 trials and exhaustive reviews, the team managed to achieve a time of 16 min per changeover. The operators took charge of making it work and the defect level is now “Zero”. This was followed up with a project on reducing wire breakage so that the problem of “loose wire” can be controlled at source and the entire rewinding operation can be eliminated.
Apart from a breakthrough in quality and release in capacity the project had a major intangible impact. Firstly, it broke the shop floor myth that these tools work only in certain industries. Secondly, operators from other areas wanted to know when a similar exercise will be done for them.
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