Answer: Because it has the extreme potential to save a lot of money. The general mentality these days, with regards to inductive proximity sensing, has been, “Lowest price wins the business”. Some manufacturers and industrial consumers alike have been accused of treating these devices as true commodities. Some salespeople have also caved in over the years with regards to price pressures in exchange for the big win. We’re all guilty to a degree, for leaving money on the table and hastening price degradation for this category of automation device over the years!
Maybe a little of this is justified. As electronic device manufacturing volume increases, prices for sub-components used to make these sensing devices decrease while manufacturing methodologies become more streamlined. The result is that cost comes out, prices drop and the game becomes more globally competitive. But with regards to application specific, hostile sensing applications, there must be a paradigm shift otherwise consumption can become gargantuan, both for material and for labor costs in the real world of factory automation. Using “generic” non-application-specific sensors in rotten environments, like welding for parts presence or Poke-Yoke applications, creates a problem. “Generic” sensors fail with regularity, change out becomes a massive maintenance issue, machine down time becomes costly and even bad parts can potentially be made (a really bad problem….audits and everything associated with shipping bad parts must obviously be avoided as much as possible).
This is the reason the truly application-specific Bunker Prox was created. It’s made in one common 18mm size (most common in structural welding disciplines), is essentially a fortress against abuse and in beta site testing, outlasted everything we’ve seen in the market, even when mounted sans heavy mounting hardware, exposed and naked to the world of physical abuse. Parts loading impact, extreme temperature bursts (typical in many MIG welding applications) and accumulated weld debris doesn’t kill it.
In multiple beta site testing locations, every test sensor was functioning between installation time and removal for “autopsy” following the designated time trial. All maintenance/engineering people who participated balked at having to remove the test sensors. In one case, maintenance personnel actually refused to remove it and the product was still functioning after 2 years in a particularly vulnerable location where a steel faced 30mm inductive proximity sensor was previously used….and where replacement occurred at least three times a week. The customer, a Tier 1 supplier to the automotive industry (before closure when the economy tanked in 2008-2009), estimated they probably would have consumed 150-200 sensors in the first year alone…in ONE single weld cell sensor location! Maintenance replacement time alone was estimated to have been in the neighborhood of 1,650 to 2,200 minutes for the year and at $385 per minute in chargeable maintenance time (and 11 minutes for change out), approximately $635,000 to $847,000 worth of maintenance time in itself was saved. Material costs (sensors) were miniscule by comparison, estimated to be between $4,500 and $6,000 (less replacement connectivity products).
In another evaluation (see pictures below), two Bunker Prox test sensors were installed in a steering cross member weld fixture where sensor life was good for 359 to 900 parts before change out on either side was required (sensor life depended much upon the operator’s technique in loading parts and the temperature proximity of the weld head to the sensing device). Upon removal for autopsy, the pair of Bunker Prox sensors continued to work perfectly after 2,400 parts. Maintenance people in this beta site were also reluctant to remove the beta test site Bunker Prox sensors.
In horrible sensing applications, it may just pay to “Think Application Specific” first. What do you think?