Derek Korn

Derek Korn joined Modern Machine Shop in 2004, but has been writing about manufacturing since 1997. His mechanical engineering degree from the University of Cincinnati’s College of Applied Science provides a solid foundation for understanding and explaining how innovative shops apply advanced machining technologies. As you might gather from this photo, he’s the car guy of the MMS bunch. But his ’55 Chevy isn’t as nice as the hotrod he’s standing next to. In fact, his car needs a right-front fender spear if you know anybody willing to part with one.

Posted by: Derek Korn 2. April 2015

Improving Lighting Quality, Lowering Lighting Costs

These before and after shots show the difference in lighting quality at Kenwal’s production facility since adding an intelligent LED lighting system.

Kenwal Steel Corp. in Dearborn, Michigan, isn’t a company we’d profile in the magazine. It’s a flat-rolled steel distributor, not a machine shop. However, the concepts it is applying in terms of improving lighting conditions in its facility and lowering lighting costs could be leveraged by a machine shop.

When Kenwal management was confronted with the need to replace aging 1,000-watt metal halide fixtures within its production facility, they reached out to Total Source LED to evaluate their options. The team initially evaluated both T5 fluorescent and LED lighting options. However, they were reluctant to replace the facility’s 369 metal halide fixtures with 6-lamp T5 fluorescents, which would result in more than 2,200 lamps to maintain. Instead, the team turned their attention toward high-efficiency, maintenance-free LED lighting alternatives, deciding to install an Intelligent LED Lighting System from Digital Lumens. This system resulted in a 93-percent savings in annual lighting-related energy costs, an investment payback period of less than one year with a return on investment (ROI) of more than 124 percent, reduced fixture counts by more than 60 percent, and higher lighting quality and illumination levels throughout the facility.

The team also recognized that intelligent LEDs (with integrated controls, wireless networking and sensors in every fixture) would have a significant impact on their budgets in a rising utility rate environment. This is because, in addition to wattage-based savings, the Intelligent Lighting System would enable them to:

  • Automatically turn off lighting within its massive steel storage area when overhead crane operators were not actively picking stock for its pickling operations and instantly back on when needed.
  • Leverage the independently rotatable and dimmable light bars within each fixture to direct lighting to work surfaces within the production area, eliminating the need to over-light space while providing better lighting for inspection operations.
  • Dim aisle lighting to 20 percent in lower-traffic areas when employees were not present, reducing energy usage while providing background and security lighting.
  • Leverage daylight from open bay doors in the facility’s shipping and receiving areas via integrated daylight-harvesting sensors in each fixture.
  • Schedule automatic changes to lighting behaviors, such as shorter timeout settings and increased dimming factors during weekends and holidays when employees typically aren’t present within the facility.

For any timeframe needed, the Kenwal team now also has access to a wide range of energy usage and occupancy data, which is accessed through the system’s LightRules lighting management software. Data that are visually depicted on interactive maps of the mill facility that can also be used to change fixture settings and behaviors enables management to:

  • Quickly report, down to the kWh, how much energy is used by fixture, zone or facility, and document the efficiency savings.
  • Observe when peak usage occurs in different areas of the facility and change settings such as fixture timeout delays to match actual operating conditions.
  • Track occupancy patterns, enabling the optimization of lighting to support high-transit, -occupancy or -usage areas, and vice versa.
  • Collect other energy management and operational efficiency metrics.

“Tracking a wide variety of decision-making metrics surrounding lighting and energy use is the secret to achieving upwards of 90 percent energy savings over T5 and metal halide fixtures,” said Ron Cimino, CEO of Total Source LED.

Posted by: Derek Korn 25. March 2015

Micromachining Tidbits

Improvement in micro-tool geometries and finishes have been key to enabling Challenge Machine to get the most out of its high-speed equipment. The shop uses tools as small as 0.001 inch in diameter.

Micromachining is becoming a bigger part of Challenge Machine’s business. In fact, I profile their efforts in this article.

During my visit to the Blaine, Minnesota, shop, I picked up on a few tricks it uses to be more effective at machining micro features. Here are a few I cite in the article above:

  • The shop sometimes starts the creation of square-edge micro-slots by first using a ball end mill to essentially rough out the slot before coming back with a standard end mill to create the sharp corners. This minimizes the load on the standard end mill.
  • Pecking cycles are used for some micro-drilling operations, and the pecking feed distance depends on the material and hole size. However, Challenge Machine has found that some applications lend themselves to drilling without pecking. This is often the case for polyetheretherketone (PEEK), requiring an adjustment of speeds and feeds to generate the proper chip size per tooth so chips can be evacuated out of the hole.
  • The shop tries to integrate deburring operations during the machining cycle as much as possible to minimize manual deburring work. If face milling is required after holes are drilled, the shop might slowly run a drill backward down each hole to remove any burrs that milling created.
  • Challenge Machine also commonly provides micromachining lessons to its customers. For nearly every prototype project, the shop works closely with the customer to offer design-for-manufacturability (DFM) suggestions. For example, a part with a callout for a 0.001-inch tip radius would require the shop to use a 0.002-inch-diameter tool. If the designer can accept a 0.0015-inch tip radius, then the shop can use a cutter with a 0.003-inch diameter to speed the machining process.
Posted by: Derek Korn 17. March 2015

Two in One

Switzerland’s Reiden Technik is new to the U.S. market. Its five-axis machine tools are available through Cincinnati, Ohio’s Pilsen Imports, which also offers large Toshulin vertical turning machines and Colgar horizontal boring mills.

Reiden has developed an interesting concept it calls Double-Drive Technology (DDT). This features two separate spindle motors in one spindle housing to enable its RX series machines to effectively perform both roughing and finishing operations. A hydraulic circuit is used to engage the high-torque spindle motor via a bevel gear coupling while the high-speed spindle motor freewheels. When the hydraulic circuit is off, the bevel gear on the high-torque spindle motor retracts to enable the high-speed spindle to be used. Learn more.

Posted by: Derek Korn 4. March 2015

One More Problem?

I recently sat in on a roundtable discussion hosted by Gosiger that drew a handful of shop owners/managers in the Cincinnati/Dayton, Ohio area. The first question asked by Norm Vallone, president of MessageWorks who led the discussion on behalf of Gosiger, related to the prime challenges those shop principals faced. Not surprisingly, many pointed to the difficulty finding/growing good employees.

I wonder if this a problem that will be exacerbated because a growing number of young people don’t seem to be mechanically inclined or handy in general. Read this and consider commenting with your thoughts.

Posted by: Derek Korn 19. February 2015

Mind the Tool Center Height When Turning Small Diameters

Louis Trumpet with Vallorbs Jewel Company in Bird-In-Hand, Pennsylvania, wrote a piece that reminds us how small turned diameters can vary from their nominal dimension when a lathe’s tool center height is off. What follows is what he sent to me (which I’ve only mildly edited).

From Louis: Very small, precision turned parts may have several different diameters, making for complications here and there. For example, when turning these small parts, you may notice that when one diameter is on the nominal dimension while others may be off by several tenths. At first, you might think this is caused by different tool pressure at the different depth of cuts, but that’s unlikely. To be sure the problem isn’t mechanical, check for backlash, flex in the machine/toolholder and the fit of the material to the guide bushing (when using a Swiss-type lathe). If everything checks out, and you’re still experiencing a differential, the likely culprit is that your turning tool center height is off.  The following example shows how being off center can affect the diameters being turned.

First, let’s assume that if your tool was brought to XO, the tip would be dead on the centerline of the bar. Line “A” is how far your tool is off center. Line “B” is your programmed X-axis dimension. Line “C” is the actual distance to the cutting edge of the tool or half the actual turned diameter dimension on your work.

Imagine making line “B” longer and longer (turning progressively larger diameters), and you see that angle “A” flattens out, which in turn will make line “C” shorter relative to line “B.” In other words, the error becomes less the larger the diameter your turn is. So, when turning very small diameters, it is critical to be on center.

The Pythagorean Theorem tells us that a2 + b2 = c2. Using that information, let’s assume your tool is 0.003 inch off center and you are turning a 0.030-inch diameter (side a = 0.003 inch, side b = 0.015 inch). Side “c” is equal to 0.0153 inch because c = √(0.0032 + 0.0152), so your turned diameter will be 0.0306 inch or will be 0.0006 inch off of nominal size.

Now assume you are using the same tool to turn a 0.0125-inch diameter. Running the same math, we find that the turned diameter (rounded) will be 0.1251 inch or 0.0001 inch off of nominal size.

Since the 0.030-inch diameter was 0.0006 inch off of nominal size, we have a differential of 0.0005 inch between the two dimensions. It follows, then, that when you offset one dimension to nominal size, the other dimension will be 0.0005 inch off of nominal. All this makes it difficult to dial in the workpiece without editing the program (bad), or using two separate offsets (nearly as bad).

You can also add a macro variable to the programmed dimension, but when you think about it, all that does is provide a convenient way for the operator to edit the programmed dimension. It’s better to fix the root cause of the problem by getting the tool on center. You can use this information to calculate how far your tool is off center and correct it with an offset, assuming you have Y-axis capability. Some small-capacity Tsugami Swiss-types have a feature built into the control to calculate the tool height using this principle, but you can see it works best at very small diameters where angle “A” and the resulting error are greater.

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