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A Case History: Teamwork Between Vendor and User Makes Good Things Happen



In the early 1980's, ErvIn Industries, Inc. initiated the Amasteel Task Force Program, conducting in-plant surveys of users' blastcleaning operating practices, followed up with seminars (based on Task Force findings), presented to the customer's Operators and Millwrights. Since then, over six hundred "Trouble-shooting the Blast-cleaning Process" seminars have been presented to users, including the subject Company.

The subject Company in this special "Case History" took Ervin's "Trouble-shooting" message to heart, studied it and analyzed It thoroughly – then made a quantum leap from the concept of "Trouble-shooting" to "TROUBLE-PREVENTION." Instead of using the guidelines the Ervin seminar presented for CORRECTING troubles, they used these same guidelines to develop a program to PREVENT troubles from occurring.

The "Trouble-Prevention" concept represents a major departure from the conventional philosophy: "If it ain't broke, don't fix it" – or, "Walt 'tll it's broke before you fix it." Before, with five blastcleaning units In operation, and given the self-destruct nature of the blastcleaning process, inevitably something became "broke" almost daily on one or more of the units. The new philosophy is: "Fix it so It won't get 'broke' during the next week's production run." This Is preventative maintenance to the max! It works!


Operated 5 blast units 3 shifts/day, 7 days/week. Because of things that "broke" and the necessary machine down-time, it was impossible to meet "just-in-time" shipment commitments.


Operate only 4 blast units 3 shifts/day, 4 days/week, and clean 50% more tons than before. There are virtually no "surprise" blast-equipment failures, so "just-in-time " commitments are met.

The Trouble-Prevention program not only makes many more blast-hours available, but also guarantees more productivity per blast-hour – i.e., shorter cleaning cycles.

Universally, the words, "Production equipment is shut down for repairs," sends shock waves all the way up a company 's management ladder – doubly so, if "just-in time" shipment Is involved. For this customer, a plus-feature of the "Trouble-Prevention" concept was the assurance that "just-in-time" commitments would be met.

Developing leadership qualities in its employees is a trademark of our Case History subject company. The leadership training courses given are extensive and comprehensive, enabling participants to fully understand and appreciate the basic operating philosophy and principles of the Company. It was the leadership qualities acquired and exercised by those involved in the Finishing Department that resulted in what can now truly be described as a world-class blastcleaning operation.

Posted prominently in key areas of the customer's Finishing Department are copies of the Ervin Amasteel Trouble-shooting Poster, which highlights three variables that account for 90% or more of all problems adversely affecting the quality of finish, productivity, and operating costs. The three key variables are:

  • Misdirection of the abrasive blast-stream.
  • Insufficient abrasive flow (low amperage readings).
  • Unbalanced abrasive work-mix (too coarse or too fine).

The Amasteel Poster lists 17 Guideline items essential to controlling these variables. Involvement of both the Operating Team and Maintenance Team is essential.

Emphasized in the Ervin seminars is this: Blastcleaning-profiling is an impact process – cast steel abrasive, thrown at a velocity of 245 fps, develops incredible force – as much as 10 million pounds per square inch. Thus, when the abrasive impacts the work-piece, surface contaminant is immediately pulverized into dust, and at the same time, the abrasive creates an anchor pattern profile on the work. The key, of course, is to be sure the force of the blast-stream is not misdirected. The abrasive should be blasting the work-piece, not the blast equipment.

The heart of the centrifugal-blast system is the wheel. With as much as 1/2-ton or more steel abrasive passing through the wheel and its componentry every minute, wear is inevitable. While there is an amazing degree of built-in wear-tolerance in these parts, once wear exceeds the limits shown in the Amasteel Trouble-shooting guidelines, misdirection of the blast-stream occurs, and efficiency is decimated.

Further, when 1/2-ton or more steel abrasive, plus contaminant fines, goes through the separator and air-wash system every minute. wear obviously occurs, adversely affecting proper separation, throwing out of balance the work-mix size-distribution, which, in turn, can cause incomplete contaminant removal, and/or lead to increased blast-cycle time or re-blast, reducing productivity by one-half to two-thirds, or more.

There is an important distinction between parts being "broke" vs. parts with "excessive wear.” Parts that are "broke" can shut the equipment down – NOW! Parts worn to excess, let you continue operating, but with the adverse results listed above. The message of how much trouble "broke" equipment – or excess equipment wear, short of being "broke," – can cause, totally registered with the customer, and led to development of the "Trouble-Prevention" concept.

Leadership cooperation between the Operations Team and Maintenance led to establishment of two separate Process Control checklists – one for Operators, and one for Millwrights. Seeing the extensive checking required by Maintenance to prevent the troubles caused by the three key variables listed above, the decision was made that one of the 5 production blast units would be shut down one day each week for Preventive Maintenance (one on Monday, one on Tuesday, etc.). With five production units involved, and one unit shut down a day, it meant four units would be available for production each day. Importantly, this also established the run-time – once back in production, each unit was to operate, trouble-free, until its next scheduled Preventive Maintenance session, a full week later!

Actual experience has shown that, on average, less than 3 to 4 hours is required to perform the items called for by the Preventive Maintenance checklist. Thus, the unit could be put into service that same day for two-plus shifts, if necessary. A most important aspect of the Trouble-Prevention program is that the actual time involved to complete the Preventive Maintenance procedure for one unit on its designated day, is much less than the time required for each "something broke" shut-down of prior years, when one part could fail one day, another part of the same unit could fail the next day, etc., and, sometimes two or more machines could be "broke" the same day. Disaster!

The Trouble-Prevention Program: Process Control of the three key variables:
Control of blast-stream direction:

On its designated checklist day, the unit's blast-wheel assembly, housing, and drive are inspected by the Maintenance Team, as to condition, i.e., free of holes or excessive wear – and replaced when needed. The blast-pattern is checked – and adjusted when necessary. During the subsequent week's run, the Operators' Process Control checklist calls for observation of the blast-pattern, every shift, to make sure it is on target, and cleaning time has not increased.

Control of the abrasive flow volume:

Posted at each blast-unit is the optimum, required ammeter reading, with a tolerance of one amp, plus/minus. The Operators' Process Control checklist calls for observation, each shift, of both the ammeter reading and cleaning cycle-time – are they as they should be? Process Control charts tell the story.

Control of the work-mix size distribution:

(An unbalanced work-mix causes poor finish, low productivity, and out-of-sight operating costs). Additions of new abrasive are made, each shift, with Operators making sure the abrasive hopper is maintained at 3/4 level, minimum. This is half the battle of maintaining a balanced work-mix – the other half is the air-wash separator setting, which is checked on the designated Preventive Maintenance day. An Ervin Spot-check Gauge is used for a quick, one-minute check as to work-mix balance – if out of the control parameters, the air-wash separator is adjusted immediately, to be sure sand fines are not In the work-mix, and that the air-wash removes contaminant plus spent shot or grit only – not usable abrasive. The Operators' Process Control checklist also calls for observation, each shift, as to possible plugging of scalp screens, and effectiveness of flapper valves on separator discard pipes.

Essential to the success of the program: Use of Process Control Charts!

The results of the customer's "TROUBLE-PREVENTION" program bear repeating:


Operated 5 blast units 3 shifts/day, 7 days/week. Because of things that "broke" and the necessary machine down-time, it was impossible to meet "just-in-time" shipment commitments.


Operate only 4 blast units 3 shifts/day, 4 days/week, and clean 50% more tons than before. There are virtually no "surprise" blast-equipment failures, so "just-in-time" commitments are met.

The AFTER tells what can happen when there's teamwork between vendor and user!



Trouble Shooting The Blastcleaning Process

problems vs major causes

Guidelines for controlling the three basic blastcleaning operating variables

These three variables account for as much as 90% of all problems adversely affecting quality of finish, cleaning productivity, and operation costs.

guidelines basic cleaning

Download the Technical Bulletin here.


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