Metal Finishing Guide Book

2013

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cleaning, pretreatment & surface preparation SIX WAYS TO BETTER BLASTING BY MARK HANNA, DAWSON-MACDONALD COMPANY, WILMINGTON, MASS. If your shop regularly uses blast prep, our tips can make your blasting operation clean, effective, and profitable. 1. REDUCE BLASTING COSTS Here's a paradox no one wants to hear: Maybe, just maybe, your blasting is costing a lot because you've invested too little money (or attention). It's easy to focus on initial capital costs. But don't overlook operational costs, which can add up quickly. Have a payback timeline in mind, and add your capital costs to projected operational costs over that time horizon – and you may find that a little more investment in equipment can make your operation much more profitable. So, exactly what are the costs to factor in?   Capital: Operational: • Equipment • Installation & training • Tax & freight • Depreciation • Direct labor + any benefits • Media with its incoming freight • Compressed air (electrical) • Maintenance – labor • Maintenance – wear parts • Disposal (spent media & dust) • Opportunity costs Reduce labor costs Many owners would guess that material or compressed air cost the most. However, in most situations it is labor. So do what is needed to cut down on labor. This can be as simple as investing in an "abrasive upgrade," a stationary gun holder, a different type of blast gun, or pre-packaged system conversion. But where warranted, a whole new system – perhaps including automation – may also be in order. Paying a worker to blast six or eight hours a day – when the same work could be accomplished in a fraction of that time – is wasteful. In addition, fewer hours spent blasting will reduce overall consumption of compressed air energy, and media, and save wear and tear. Understand media How did you select the media you are using? For some, it's easy: it is in the spec. For others, it's what they've always used. Many people buy media by how much it costs per pound – or bag. That can be a mistake. Today, there are dozens of media (type & size), and many are excellent. The one that will give you the best results the fastest – and hold up the longest – will also be the cheapest to use, regardless of the initial cost. Select the right media for the job, and your major – sometimes hidden – costs will diminish, because you're blasting fast and clean. On the other hand, "cheap media" is often slow and dusty, reducing visibility (which increases rework). Inconsistent blast quality and a poor and possibly unhealthy working environment become factors. Add in extra needed maintenance, freight and disposal costs, and saving cents on media makes no sense at all. (See section: "How to Select Blast Media" at the end of this article.) 10

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