Minimum quantity lubrication (MQL) has great potential for assisting in machining a wide spectrum of materials. As manufacturers continuously seek to reduce manufacturing costs, waste and improve health and safety profiles, this technology can help in the drive to get there.
So says Optis, a joint venture between TechSolve and Castrol. According to Optis, flood coolant uses as much as 60,000 ml of fluid per hour, while MQL typically uses less than 500 ml per hour. This is due to the coating of the interface between the tool and the material being cut with a thin film of lubricant, preventing heat build-up caused by friction. This significantly reduces the amount of fluid that needs to be procured, maintained and disposed of, saving money, manpower, and health and safety issues associated with residual fluid and contaminated chips.
When properly applied, whether externally or through the tool, MQL can lead to improved surface finish and increased tool life. It also has a positive impact on emissions and waste, boosting a facility’s overall health, safety and environmental profile.
According to Optis, the cumulative cost of cutting fluid can total as much as 15 percent of a part’s total production cost. Therefore, minimizing its use has major cost-efficiency implications for manufacturers. Also, there are many routes to doing so with many cutting operations primed to benefit from MQL, including turning, milling, drilling, circular and band sawing, reaming, tapping, routing and broaching.
However, despite the opportunities and benefits MQL machining can offer, there are still challenges to overcome and some key considerations in implementation:
MQL does not have comparable chip evacuation abilities to those of wet machining.
MQL is still not well suited for deep-hole drilling, energy-intensive processes such as grinding, special operations like honing and small-hole drilling, or for difficult-to-machine materials such as titanium and nickel-based alloys.
MQL still produces a very fine mist, which can be more difficult to filter.
MQL implementation may require changes to the machine tool and processing strategy.
Despite these challenges, Optis says MQL provides a cleaner, greener alternative to classic fluid supply, on which could take manufacturers forward in embracing sustainability initiatives and implementing “Factory of the Future” capabilities. However, industry update has been relatively low so far. This reticence may be due to how counterintuitive it seems that using less fluid will yield the same cooling and lubricating properties as traditional flood or high-pressure systems. The fluid itself must be carefully selected based on the material that’s being cut, and its application must be carefully considered based on tooling , type of operation, cutting parameters and machine tool being used, the company says.
Recently I was invited to attend a talk on additive manufacturing hosted by the local chapter of the Product Development and Management Association (PDMA). My email invitation included a link to the Cincinnati PDMA Meetup group, which the organization used to set up and coordinate the details for this event.
If you’re not familiar with Meetup (I wasn’t), it’s a social network that allows users to create virtual groups based on interests that get together in the real world. Once you join a Meetup group, you can RSVP for its events, connect with other members and even contribute to crowdfunding to help pay for things like refreshments. It’s an interesting mix of social media and real-world networking and learning opportunities.
What struck me most about the PDMA Meetup was the free exchange of knowledge among the people at the event. Attendees ranged from manufacturers currently using additive manufacturing to those just learning about this technology or seeing it up close for the first time. The Meetup was a way for those newcomers to learn from others with direct experience, ask questions, and make contacts for follow ups. Maybe some of those relationships will lead to contracts or collaborations.
There are two newsletters that Modern Machine Shop emails to subscribers that serve as nice complements to the print magazine. Twice a month, we send out our “MMS Extra” newsletter that builds on the magazine by offering additional insights into the work and business of machining. Regular topics include unique shop innovations, newly posted products, the latest videos and more.
We also offer a weekly blog wrap-up newsletter that emails each Friday, as we don’t expect that you’ll have time to visit this blog every day. “The Shop” weekly newsletter gives you quick descriptions of the blog posts that appeared that week so you can read them at your own convenience. Topics include breaking industry news, road reports from tradeshows and additional insights that we can’t squeeze into our monthly print magazine.
Sign up to receive these free newsletters. That page also includes descriptions of newsletters from other Gardner Business Media brands covering additive manufacturing, automotive, composites, moldmaking, plastics and other industries and technologies.
Microfluidics industry R&D applications have called for milling channels with extremely smooth finishes into plastic or, as seen here, titanium plates. The channel here measures 0.006 inch and requires a 0.2 µm surface finish.
This July-issue feature article tells the story of how a single machine tool catalyzed a massive transformation at Integral Machining, a 6,000-square-foot contract manufacturer in the Toronto area. Thanks largely to the addition of Kern Microtechnik’s five-axis Evo, the shop is serving new customers that often demand tolerances measured in single-digit microns—far greater precision than anything it had handled before. What’s more, lessons learned in the process have helped improve operations on less demanding work as well.
However, the machine alone wasn’t enough. This shop had to learn new strategies in order push it beyond its advertised precision of ±2 µm on the part. Indeed, the more I talked to Andrew Sweeting, the machine’s chief operator, the more he reminded me of a smartphone “power user” (these are the people who really dive deep; they seem to have an app for everything, use mountains of data, and might even be willing to dive into the firmware to customize their device). Here are a few examples of thinking beyond standard features and functions:
Finding the kinematic point. Most five-axis machine tools are permanently configured that way—that is, the fourth and fifth axes are a permanent, integral part of the overall structure. That’s not the case with the Kern Evo. According to this machine tool builder, every machine has an “accuracy budget,” and each added component—an additional axis, a tool changer—detracts from that budget. To facilitate the kind of precision Integral Machining is achieving, the machine’s fourth/fifth axis table is installed only for the applications that require it.
For any job requiring tolerances tighter than about 5 µm, a crucial step in installing the table is finding the kinematic point, or the theoretical center about which the table pivots. Boiled down to its essence, this complex procedure involves moving the axes through their range of motion, stopping for periodic measurements against a standard with known dimensions (in this case, a System 3R chuck), and using the compensation tables in the Heidenhain iTNC530 CNC to adjust for error within four decimal places (0.0001 degrees).
Actively managing thermal compensation. With small, precise work, temperature is always a concern. That’s where the machine’s temperature management system comes into play, not to mention tight environmental controls in the segregated area of the shop where it’s housed. However, when surface finish presents just as much of a challenge as part geometry, simply letting the machine’s automatic thermal compensation system do its thing may well be a mistake.
For example, one job (pictured above) involved machining tiny channels into a titanium plate for a microfluidics R&D application. Trochoidal climb milling with a 0.004" end mill proved an efficient means of producing the slots to dimensional specifications. However, achieving 0.2 µm surface finish specification was another matter. Based on advice from Kern, the machine ran without cutting for about 15 min. (sufficient time for the tool assembly to “grow” to its fullest extent), then switched off Z-axis thermal compensation while the tool was in the cut. Reserved only for specific workpiece features with exceptionally stringent surface finish specifications, this strategy prevents the microscopic “hammering” motion resulting from the machine’s automatic response to temperature fluctuations.
Scoping out problems and sweet spots. To my knowledge, most manufacturers would never have reason to use the oscilloscope function of the machine’s CNC. Typically employed by machine tool builders and distributors for axis tuning, the oscilloscope measures electrical signals to determine the difference between the axes’ programmed positions and actual positions. Integral Machining, however, has learned to effectively employ this function for troubleshooting and for determining “sweet spot” cutting parameters that provide the smoothest machining for various cutting tools.
To learn more about how Integral Machining leverages the oscilloscope (and the Kern Evo generally), read the full article.
These inserts for expanded-beam fiber-optic cable connectors use the green lenses to focus and transmit light from one optical fiber to another. The bores holding the optical fibers were held to within +1.5/-0 µm of nominal diameter, positioning within ± 1.5 µm, and an N4-level (0.2- µm) surface finish.
“Your comment that the Japanese do not listen to music while working reminded me of a video that we show in our shop to new employees. Despite what people think about their ability to multitask, the human mind can really only focus on one task at a time. You can either listen to music or work with your hands. Take a few minutes to watch this YouTube video [embedded above].”
He went on to say: “I have been showing this video for a couple of years. The reason: our millennials. I have watched our youngest employees bouncing to the music in their headphones while either punching offsets into the controls of our very expensive CNC production equipment or ensuring the quality of our customers’ parts. We want them to enjoy their time at work, but they also need to understand their responsibility to our stakeholders to be productive in an extremely competitive global market.
“I banned the headphones. They are a distraction as well as a safety concern. While I have not banned cell phone use in the building, I have stressed that its use should be appropriate to work. Focus!
“That focus is important. We stress to the staff that anyone with several million dollars can buy every piece of equipment we own. There is nothing unique about the Tornos Deco, Tsugami, Index, Euroturn or Miyano equipment that we own. The only competitive advantage that we have is each team member’s brain working in conjunction with the brains of their co-workers.”