Peter Zelinski has been a writer and editor for Modern Machine Shop for more than a decade. One of the aspects of this work that he enjoys the most is visiting machining facilities to learn about the manufacturing technology, systems and strategies they have adopted, and the successes they’ve realized as a result. Pete earned his degree in mechanical engineering from the University of Cincinnati, and he first learned about machining by running and programming machine tools in a metalworking laboratory within GE Aircraft Engines. Follow Pete on Twitter at Z_Axis_MMS.
Chatter is self-excited vibration. We often think of controlling chatter as a challenge that relates to milling. However, chatter can be a factor in turning, too. This video from Haas Automation describes “Spindle Speed Variation,” a parameter in the company’s CNC that addresses chatter on lathes.
As the name implies, this parameter allows the lathe spindle speed to automatically vary. The user sets the speed variation envelope (say, ±100 rpm) along with the period of time for cycling through this range (in increments of 0.1 second). In the video, a lathe running at 2,000 rpm ±100 rpm is seen under a strobe light. The strobe picks up the speed variation, making it look as though the spindle is rocking back and forth.
This solution works to overcome chatter because chatter is speed-specific. Certain spindle speed values resonate with the overall machining system. Varying the rpm potentially stabilizes the cut because it means that the lathe spends only an instant at a time at any problematic speed.
The video illustrates the impact by showing the turning of a long bar, unsupported by a tailstock. The bar chatters when turned at consist speed, but then can be turned precisely and quietly once the variable speed is turned on.
A small slice of the infographic. Click on the link below to see the entire illustration.
MMS’s outreach to future manufacturing professionals typically focuses on careers in machining. A closely related field is welding, and the Tulsa Welding School has recently produced a detailed infographic summarizing the work, opportunities and compensation in this field. Most of the jobs are in manufacturing, but the illustration points out the traveling job opportunities as well. It also notes the increasing extent to which welding work involves automation. For the benefit of a young person in your life who might make a good welder or welding technician, find the complete infographic here.
I’ve noticed how some shops here and there have improved their lighting, recognizing that both the accuracy and the psychology of the shop stand to improve with better ambient light.
3V Precision has arguably taken the next step, giving thought to ambient sound. In this Tacoma, Washington, job shop, there are no competing radios at different toolboxes, or boomboxes struggling to be heard over the machines. Instead, a sound system appropriate to the shop’s noise and acoustics has been installed with speakers mounted high above the machines. Two of those speakers are visible in this photo. As the machine tools run here, upbeat music playing through them can be heard at a level that does not seem loud, but nevertheless comes through clearly enough to sing along.
The music is selected by shop owner Peter Boucher, and he keeps it light. Read more about Mr. Boucher, 3V Precision and this shop’s attention to employees.
CAM developer Delcam and cutting tool supplier Technicut produced this brief video illustrating the highlights of a machining cycle that generated a blisk from an 804-mm diameter disk of titanium 6-4 in 35 hours. The two companies say that cycle time is less than half of what would be required to machine this same part with conventional methods. In the cycle shown, several factors contributed to that productivity:
Roughing is performed in stages throughout the process. Lower sections of blades are left in their rough state to maintain stiffness while the upper portion is being machined.
Tool paths specific to blisk machining programmed in Delcam’s PowerMill use barrel cutters from Technicut for semi-finishing and finishing. Offering a larger radius at the cutting surface than ballnose cutters, barrel cutters achieve the same cusp height between passes as a ballnose tool with a stepdown that can be three to four times as large.
Initial rough machining operations between the blades use Technicut’s Titan X-Treme Ripper end mill not only to remove material quickly but also to relieve stresses in the material introduced by forging.
Blisks—one-piece bladed disks—are increasingly used in turbine engines in place of individual blades machined separately and fixed into a hub. The completed blisk in this video has 31 blades, each 84 mm long with a root radius of 4 mm and scallop height of 10 microns.
What is the next important step for your machining facility? How will you improve your shop’s process or prospects in the coming year?
Based on steps that other machining facilities have taken, and based on ideas we’ve recently explored in MMS, here are 10 possibilities for you to consider:
1. Automate (particularly with a robot).
Say “automation,” and the picture of a robot is probably what comes to mind. Automation is, of course, a much bigger idea than this, and there are different and simpler ways to realize a more automated process than robotic automation. That said, a robot is among the most powerful and versatile automation tools. This year, take another look at automation, and take another look at a robot in particular. Two small makers of motorcycle parts are showing how to achieve flexible responses to surges in demand through robotic automation.
2. Put performance on display.
Let the employees on the shop floor see exactly the same production metrics that the facility’s managers are watching. One way to do this is with a monitor displaying the performance in real time. Just making the metrics public and visible often leads to direct and measurable improvement in those numbers.
3. Rework your shifts.
Coordinating work across three shifts per day can be complex, and the third shift is often incomplete because it is so hard to staff. A variety of benefits can come from replacing the system of three eight-hour shifts in a five-day workweek with two 10-hour shifts in a four-day week.
4. Size up your software.
Inefficient equipment is easy to spot. Inefficiencies resulting from software limitations are harder to notice. Hardest of all to see are the inefficiencies resulting from software that the shop lacks altogether. Many machining facilities have been surprised to discover the value and impact of software improvements, particularly the adoption of ERP.
5. Look to additive manufacturing.
Additive manufacturing has the potential to transform part designs, lead times and supply chains. In metals, the capability is challenging and costly—it might not be time yet for your shop to invest in additive manufacturing. However, it is time to be aware of this technology and its emerging promise for the industries you serve.
6. Use a 3D printer.
Once you buy a 3D printer, even a small and relatively inexpensive one, it can be difficult not to use it. The freedom it gives the shop to generate customized, functional objects can provide the answer to many nagging shopfloor problems that previously went unaddressed. That was what this shop discovered.
7. Find the waste.
Non-value-added activity is pervasive in manufacturing. Arguably, there are eight major ways that manufacturing processes routinely waste effort and time. Many of the wasteful steps are invisible, because they are an unexamined part of what the shop does routinely. Walk through your shop and your processes specifically looking for these various types of waste.
8. Bring discipline to devices.
The distraction of employees’ personal devices can be a source of inefficiency. The cameras in those devices poses a security risk in the case of sensitive parts. When this shop owner banned shopfloor cellphone use, he saw measurable productivity gains and received some surprising feedback.
9. Identify the challenge that suggests the next advance.
Challenges often arise gradually. It is easy to accept some slowly growing difficulty as just a chronic problem that has become a bit worse over time. But that growing difficulty might be a sea change. A medical component maker provides a useful illustration in identifying challenges and changing practices to adapt.
A group of independent small shops working together can achieve many of the advantages of a large manufacturer. That is what this coalition of shops discovered, an active and mutually beneficial alliance of shops that even includes some competitors.
11. Bonus idea: Keep reading.
All the links within the 10 ideas above connect to articles and resources published in 2015. Make it a regular habit of reading Modern Machine Shop throughout the coming year to find more ideas like these. Subscribe here or renew your subscription.