|Ask the Experts|
October 26, 2020
Pick and Place Machine Calibration
In general how often should we calibrate pick and place machines, or run a placement machine process capability index Cpk test?
|Expert Panel Responses|
We would suggest you follow your manufacturers guidelines for the frequency of calibration. It is also recommended to conduct a Cpk test after the placement equipment is moved especially if it is transferred from another facility since movement during shipment can affect the accuracy of the system.
A placement machine calibration should be run every six months.
North America Sales Manager
Depending on the type of pick and place machine you have will determine how often and when to calibrate. There are several systems within these machines that would require a different calibration procedure for various reasons. There are vision and camera calibrations, place area calibrations, tools and/or tool banks etc. Most systems need calibration of their particular subsystem when a component has been replaced or adjusted.
It would be best to check with your equipment manufacturer and see what they recommend. If you are having placement issues, you may need to calibrate only those systems causing the issue. Many of these calibrations must be done in a specific order and may have prerequisites that must be performed. I would check with your manufacturer and see what they suggest for your equipment.
Manufacturing Applications Specialist
CeTaQ's global independent Cpk measurement service has measured over 20,000 SMT machines in nearly 25 years. All types, all OEM's, all objective unbiased validations.
Normally, machines are validated every year. Historically, upon annual re-cert, 80-90% of those machines fail OEM specification. Those statistics tell us that the machines need either OEM calibration or a quality optimization of performance, more specifically, placement offset adjustments more often. More often means less than one year, more likely in the 6-9 month range for regular monitoring of accuracy calibration.
The optimization needs to consider all head and angle associations to get the best accuracy performance from the placement machine. This type of adjustment brings a higher level of accuracy that most OEM calibrations cannot achieve.
Certainly, both types of calibration can compliment each other, and often additional Cpk testing shows continued failure of OEM specification even after a full set of OEM calibrations; especially troubling for customers when the machines are brand new and yet to have first production boards even set on the conveyors.
In general, Cpk tests should be run any time major PM's have been performed, after any significant machine crashes, or after machines have been moved. Additionally, any time tracked quality data suggests there is something wrong.
As well, you cannot forget about validating placement forces by individual nozzle/spindle. Too much force and components can be micro-cracked causing eventual failure in the field
For reference, about 20 components are placed in the blink of an eye on some placement machines, so you can imagine how fast defects can happen. Regular quality checks and Cpk tests should be run in each SMT process step to maintain high quality product and efficient processes.
Calibration of Pick and Place equipment really depends on the type of equipment being used and manufactures recommendation. Throughout the company and over the years we have had several platforms, all of which are monitored for product quality daily. The platforms which have performed poorly, requiring regular calibration, have been eliminated. Current platforms are calibrated when moved or repaired and some require as part of the manufacture suggested annual preventive maintenance.
Regarding Cpk, if you are monitoring yields and efficiencies daily, then you should have all of the information you need to determine if the platforms are performing as expected.
Director of Corporate Quality Assurance
Delta Group Electronics Inc.
The equipment manufacturer has recommendations regarding the required calibration cycles. Should you have a service contract that will check your equipment let's say every 6 months, I would recommend to have the calibration as part of the bi-annual service visit.
An exception to this would be a major machine damage / incident to the main moving systems of the machine - head/nozzles, tracks, gears.
Engineering and Operations Management
|Submit A Comment|
Free Newsletter Subscription
Circuitnet is built for professionals who bear the responsibility of looking ahead, imagining the future, and preparing for it.
Insert Your Email Address