650 words text only full page; 580 with quote; 520 words with medium size image AUGUST 2008 / VOLUME 60 / ISSUE 8 staying sharp manager’s desk By Keith Jennings Old school vs. new n most machine shops, including ours, to feel worthy doesn’t make much sense and could be it’s common for older, more experienced wasting time and energy. Imetalworking professionals to work alongside Meanwhile, younger employees who rely on younger ones. Ordinarily, the younger workers would technology and aren’t desirous of frequent walks to be wise to listen to their experienced co-workers and another work area often become more productive than incorporate their techniques that have been many years their sweaty counterparts. Nonetheless, computer- in the making. minded young workers have a few hyped-but-not- There are times, however, when the unavoidable terribly-useful practices of their own. For instance, clash of generations prompts a vigorous debate about posting volumes of bandwidth-intense material old style vs. new style. Respectful debate is healthy online doesn’t seem to garner much attention in the and can provide an excellent venue for brainstorming machining trenches. Electronically recording every and troubleshooting, from which—hopefully—the process in a shop with wireless gadgets isn’t productive best practices of all are combined to create an effective either, but collecting some real-world data is better solution. Negative results than none. can occur, however, if some Those who rush around from office It’s OK to take advantage are unwilling to consider of computer-based the benefits espoused by to shop, machine to meeting, phone manufacturing technology. the other generation. Our to forklift, scrap bin to tool cage Younger workers are usually company has certainly comfortable with that experienced the old vs. new and back to the office again, while and learn quickly, so take head butting that inevitably sweating profusely probably aren’t advantage of those strengths. occurs. Also, it can be valuable After 16 years, I’m utilizing their time effectively. to use your company’s certainly not a new guy database to look for trends, anymore, but perhaps some of my ideas are. In any patterns and statistics that can open a giant window of case, I’d like to compare the generations and identify business-generating information right from your desk differences. First, let’s dispel an old-school notion without going to the shop. embraced by many experienced machinists, managers While I don’t like worn business phrases, working and owners: Computers are worthless, and you must smarter instead of harder will make it easier to grow be physically busy and hectic throughout the day to be your business. Determine how those technology- productive. That isn’t correct and makes me tired just savvy young workers can multitask without breaking thinking about it. Unfortunately, a few technology- a sweat. Effectively using older employees’ experiences challenged subordinates succumb to this belief that with today’s technology-driven ideas is critical. How creating chaos, sweating and getting dirty means you’re your shop adapts to ever-evolving conditions and a hard worker and getting much accomplished. these inevitable generational clashes will ultimately Those who rush around from office to shop, determine success. Now, excuse me while I monitor machine to meeting, phone to forklift, scrap bin my dad’s shop from a laptop in Fiji. CTE to tool cage and back to the office again, while sweating profusely, probably aren’t utilizing their time About the Author: Keith Jennings is president of Crow effectively. If an employee gets up from his desk and Corp., Tomball, Texas, a family-owned company focusing goes to the shop to clarify something, it usually takes on machining, laser cutting, metal fabrication and metal a minimum of 20 minutes, regardless of whether the stamping. He can be e-mailed at [email protected]. actual issue required a 2-minute fix. Being busy just staying sharp back to basics Measuring surface finish By Dr. LaRoux K. Gillespie Measuring a part’s surface roughness achieve the desired finish. is generally straightforward, quick and Experienced machinists have long Surface finish impacts part life, corro- inexpensive. Drawings and standards drawn a fingernail across a surface to de- sion resistance, friction, electrical contact specify what surfaces need specific fin- termine its roughness. That technique resistance, appearance, fluid flow and a ishes and where, but part designers must doesn’t meet ISO standards, but it works host of other functional characteristics. specify the best roughness parameter to until faced with a finish of 8μin. Ra or finer. A $30 electroplated, hand-held roughness comparator measures finishes produced by several machining processes down to 2μin. Ra, providing a quick, visual means to estimate the finish on turned, milled or ground parts. Zygo Corp. A 3-D roughness image from a prosthetic implant. Actual measurements are normally made using a profilometer, which drags a probe with a tip radius across the sur- face of interest. The part can be carried to the measuring device or a portable profilometer can be taken to the part. The instrument can provide strip-chart printouts that document the roughness found at any point on the part. Profilom- eters can also print any of 10 different common parameters that define rough- ness. Portable devices cost from $900 to $6,000 while standard desktop machines cost from $3,000 to $45,000. Usually, surface finishes are measured over a small area of the part, a typical area of finish. A profilometer’s stroke can be as short as 0.020" or as long as 8" to reach, for example, the bottom of an au- tomotive piston cylinder wall. Typically, the stroke length is about five times the cutoff value. Cutoff values by the U.S. standard are 0.003", 0.010", 0.030", 0.100" and 0.300", so the surface finish analyzer will be able to measure five dif- ferent sets of data when the cutoff value is set to 0.030" and the stroke is set to 0.150" or longer. staying sharp back to basics Some low-cost analog profilometers face, or topological map, and calculate seconds and can determine the finish in measure only average roughness (Ra) up to 100 different roughness values. an area as small as 0.001" in diameter, and cannot be upgraded to provide more These machines typically cost $50,000 which would be unusual, or as large as a information. Digital profilometers, al- to $100,000. The topological mapping part’s entire surface. though more expensive, provide up to 80 provides instant visual clues of what has A deep surface scratch may appear to different measurement values and allow changed and that often leads to an un- affect surface finish values, but it actually users to export the data. derstanding of how to correct an issue. has little impact on the average value be- Laser and white-light measuring ma- These machines may take as many as cause the deep scratch is only one valley chines provide a 3-D view of the sur- 300,000 surface measurements in a few among the many measured. The ANSI B46.1 standard specifies that surface fin- ish is measured in the direction that pro- vides the highest roughness value. That is normally across the feed marks. Profilometers can have three different tip radii (2, 5 and 10 microns) that reach into surface valleys. A 2-micron radius tip allows a user to measure smoother finishes more accurately. A 10-micron radius tip tends to make the surface ap- pear smoother than it is. The smaller tips, however, wear quicker and can be damaged more easily than broader tips. A profilometer manufacturer might offer up to 25 different tips or more to allow measurement in deep-hole surfaces and unusual part features. The Ra scale is the arithmetic rough- ness average. Ry, or Rmax, is the peak-to- peak roughness and is typically four times the indicated average roughness. A mir- ror finish has a roughness of about 4μin. Ra, and lapped and polished surfaces typ- ically are from 8μin. Ra to 16μin. Ra. The Rq scale is the average of the mea- sured height deviations calculated as the root mean square (rms). Ra is the average of the peak-to-valley heights, but Rq is the rms of that value. Some companies use Rz to define roughness. This value is the 10- point height: the average absolute value of the five highest peaks and five lowest valleys for the measured length. CTE About the Author: Dr. LaRoux K. Gillespie is a retired manufacturing engineer and quality- assurance manager with a 40-year history of precision machining and deburring. He is the author of 11 books on deburring and more than 200 technical reports and articles on precision machining. He can be e-mailed at [email protected]. staying sharp machine technology Progress through partnership By George Weimer agement system. “THINC allows the op- post-processor that outputs the appro- erator to know things about a job such priate G code. This has always been a Consider this premise. Machine tool as the state of tool wear,” said Curtis Rel- problem with posts.” Partnering with control technology needs to be upgraded. lick, global product manager for Ken- Mori Seiki allows CNC Software to de- The industry needs to reinvent itself nametal. “Tool Boss allows the operator liver posts in a timely fashion. Nemeth technologically and that can only be done to know things about insert needs for a also said his company has another devel- through cooperative programs with sup- given job.” Integrating those into a time- opment project with Mori Seiki that he pliers, universities and customers.