Page 24 - MetalForming March 2012

Data Collection
downtime, according to the union labor contract, for personal issues;
• Operator-related;
• Maintenance-related;
• Management-related—for train-
ing, scheduled meetings, etc.; and
• Awaiting component parts.
In addition, productivity has
climbed significantly for some part numbers, measured as cycle-time reduction, “due to our data-collection efforts and to holding the operators to a production standard,” says Sheffield. “We also use the data to initiate process improvements.”
The Clock is Ticking, Always
Data gathering at each welding cell begins when each operator logs into their cell’s HMI each morning. Greeting each operator is a welcome screen that requires the operator to agree to this statement:
I agree that I have been trained, have read, and will comply with all stan- dard operating procedures, operator inspection instructions and job-safety analyses for operating this cell.
Once he clicks the “yes” button, the clock begins to tick.
“They have up to 40 min. after pro- duction has started to run their first gauge check on a welded assembly,” says plant manager Jessie Meet. “Every inspection point (there may be as many as 14) is considered out of spec until the operator inspects it and turns it ‘green.’ Then and only then can an operator send a cell into full production.”
As the cells run, managers can access data collected from the plant floor and closely monitor production statistics. “These snapshots tell us the cell number, operator, part number being run, lot size, how many have already run and how many remain,” says Meet. “We can see how many assemblies have been stenciled with the operator’s identifier, and how many assemblies were rejected and why. And we can see log-in and log-out times, hours logged in and current hourly production rate compared to the agreed-upon standard.
“The key is being able to track idle
When an operator logs into his cell’s HMI at the beginning of each shift, he must agree to a statement reading: I agree that I have been trained, have read, and will comply with all standard operating procedures, operator inspection instructions and job-safety analy- ses for operating this cell.
22 MetalForming/March 2012
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hours,” Meet continues. “We can iden- tify problems early on, learn the caus- es and develop solutions in a very time- ly manner.”
During production, the cell HMI provides alerts to the operators regard- ing the required inspection interval. The cell shuts down automatically and prohibits the operator from continuing to run until they perform the required gauge check. As a result of building quality into the process in this way, PPM levels have dropped from a monthly high of 176 (in 2003) to a low of 3 (in 2011), where it has hovered for some time.
The last piece of data gathered at each cell, each shift, relates to safety, and has helped managers better-track recordable injuries. Before logging off at the end of their shift, operators must answer this question illuminating the HMI screen:
Did you sustain any injuries during this session of operating this cell?
A “yes” answer triggers further inves- tigation.
Reduced Internal Scrap and Rework Rates
Operator accountability and trace- ability also has reduced internal scrap and rework rates. “Component parts and weldments can’t be randomly
scrapped without accountability,” notes Meet, “since every part carries the oper- ator ID. Before, raw material to fin- ished goods was difficult if not impos- sible to track and control. We would struggle to identify where the material was going.”
From 2006 to 2011, scrap rate at the plant has dropped from 1.2 percent to 0.5 percent, and rework has dropped from 6 percent to 2 percent.
Tracking the causes of scrap and rework allows Sheffield and his team to identify the top scrap-producing parts and cells, and address issues in a time- ly manner. It also provides data to the firm’s inhouse team responsible for designing and building weld fixtures, and in some cases even has impacted the stamping-die design and build process. Northern Stamping moved weld-fixture design and build inhouse in 2007, and the investment in person- nel and equipment has paid huge div- idends. Meet offers examples:
”We recently took over a hitch job from a distressed supplier and when we put it into production, we were blowing out sensors in the weld fixture every other day. Our fixture department was able to quickly identify the problem and relocate the sensor to better pro- tect it from the welding environment. Making that change via an outsourced