By Joe Feeley, Editor in Chief
Cadence Innovation, based in Troy, Mich., is a large Automotive Tier One supplier that produces plastic injection-molded automotive interior components for several major automobile manufacturers. Quality and JIT capability are two key criteria for winning and maintaining the contracts from automotive end user customers.
A typical part starts with injection molding and then is processed through multiple secondary operations. The secondary stations typically are smaller machines in which individual parts are hand-loaded and unloaded.
When mass production rates are critical to cost-effective production, any nuisance disturbance is a big problem, says Van Smith, manufacturing engineer at Cadence. If this occurs frequently it jeopardizes part quality and delivery. When a process has a lot of nuisance faults, the operating staff stops trusting the machine and often is taught to work around the issue by resetting the fault and passing the part as good product, he explains. A creative operator learns to bypass the sensor that is creating the fault condition.
The Password Is … Worthless
The existing controls architecture of the Cadence machines consisted of a PLC with HMI. Operators were allowed to reset minor faults but needed supervisor approval via a password to access the password-protected screen in the HMI for more serious issues, explains Smith.
AUTORIZED PERSONNEL ONLY
“You would find the supervisor giving out access codes,” says Smith. “We couldn’t hold anyone accountable. We needed to prevent operators from doing arbitrary resets and limit their access, so it required a second set of eyes. It used to be just a reset button. Then it was a reset key, but everyone had a reset key. Then we went to a password, but supervisors sometimes just gave away the password because they didn’t want to be bothered. We needed to create more accountability.”
Cadence clearly needed a means to password-protect its HMI screens if it was going to have a handle on the newly available data. The company realized that passwords for critical screens were not secure, operators were resetting faults without notification or documenting faults and, even worse, bypassing quality checks.
The Most Secure Choice
“We looked at card swipes and fingerprint access,” says Smith. “Fingerprint is a pain and actually can be fooled with a gummi bear. You waste more time dealing with that more than anything else. We do have card swipes in the facility for time-clocking. You can take a card and photocopy it and swipe it. There’s no control.”
PROTECT THE PROCESS
The solution was to install a Euchner EKS reader in each secondary machine that communicates directly with the PLC and HMI. Access is allowed or denied based on having the appropriate programmed key. Operators, maintenance, supervisors and engineering personnel all have access keys with an appropriate access level. The benefit of having specific employee identification information programmed into each key is that it becomes very easy for the IT group to implement additional efficiency, productivity and maintenance tracking programs into the production management process, says Smith. In addition, the embedded employee-specific information on the key discourages lending them out due to the inherent traceability, unlike mechanical keys.
The plant is 730,000 ft2 and has almost 100 presses. “We actually experimented with the key system in 2005,” says Smith. “We put it on two or three machines to evaluate the benefits. Then in ’06, we started putting it on whole platforms and standardizing the plants on the system. Today, every piece of equipment has it. We have thousands of keys; they’re all color-coded. If it’s a green key, you know it’s an operator. A supervisor key cannot run the equipment.”
Now that everyone has a personalized key, says Smith, when that person resets a fault, a name is logged. The technician now can see a person’s name and if that name appears several times, the technician knows who to ask what the problem is. “The only way to reset the fault is for the supervisor to insert the key and reset the fault,” says Smith. He can either reset the fault or put the machine in containment.
“A few years back we wanted to do data tracking, so our service techs could pull up fault information and analyze the data sheets and see if we need to re-adjust sensors and look for recurring problems,” says Smith. “With plastic parts, they can come out warped or twisted. You have to be able to overcome that. Sometimes, you can select the wrong sensor with the wrong range during a setup. There really wasn’t a problem, per se. We were trying to improve our quality. We were looking at that as an internal improvement. That’s when the idea grew into the operator ID and time and date stamping of critical products, so it will apply a serial number to each part. Now we have a record of safety-critical parts.”