Russ Willcutt joined Gardner Business Media as associate editor of Modern Machine Shop in January of 2014. He began his publishing career at his alma mater, the University of Alabama at Birmingham (UAB), where he produced magazines for the Schools of Engineering, Business, and Medicine, among others. After working as group managing editor for the HealthSouth Corp. he joined Media Solutions Inc., where he was founding editor of Gear Solutions, Wind Systems, and Venture magazines before heading up the Health Care Division for Cahaba Media Group.
One of the most popular conference tracks at the PMPA National Technical Conference were sessions in which prints—and often part samples—with certain key parameters were provided to groups for roundtable discussions of the best way to machine the part.
When visiting a shop, I am particularly interested in the process behind determining the best way to machine a part from the prints provided by the customer. So many things must be taken into consideration—in fact, nothing can be left to chance. In order to meet the customer’s requirements, and to reach the lowest cost per part in order to win the bid, here are the top 12 considerations I’ve noted, although there are certainly more depending on the part in question:
Best machine tool/process
Risks/benefits of each process
Geometry/features of the part
How to machine with fewest setups/lowest cycle times
The best approach to workholding/fixturing
Best type of stock to use
How much cross-drilling and backworking, etc., will be required?
Best means of conducting measurement/inspection
Chip generation (types, amounts, etc.)
What is the purpose of the part?
How will deburring be accomplished?
What type of surface finish is required?
I was able to witness an especially intense example of this exercise at the recent Precision Machined Products Association (PMPA) National Technical Conference in Grand Rapids, Michigan, April 9-12 (go here for my review in Production Machining magazine). In addition to the presentations made during the three-day event—Rotary Transfer, Speeds and Feeds, CNC Programming, Additive Manufacturing, Exotic Materials, etc.—I sat in on a group discussion among operators, engineers and programmers as they worked from a blueprint to identify the optimal machines, tooling and processes for manufacturing the part in question. Three of the sessions were structured in this way.
Each team, generally consisting of five to six members, discussed the plan and the related part to begin developing a machining approach. Everything from part geometry, to material, to machining methods and tooling were examined, including deburring and surface finishing.
It was fascinating to observe the thought process behind deciding how you get from a hunk of metal to a detailed, often geometrically complex finished part with the lowest cycle times, the fewest setups, and a process where each step logically leads to the next. I’ve sat down with individual shop owners (see this article from a recent issue) as they’ve explained the logic behind their decisions, but to witness a group discussion in which everyone discussed their personal experiences—both victories and failures—and the tricks they’ve learned along the way for making deburring part of a machining step, or developing fixturing that made setups easier to accomplish gave me new respect for all the thought and planning that goes into machining parts from raw materials.
The audience was a mix of engineers, programmers and machine tool builders. Their different perspectives and experiences made for lively conversations.
At the conclusion of the discussion period, a representative of each table addressed the hall, describing the group’s machining path, including the reasoning behind the decisions they’d made. Once their presentations had been made a member of the company that provided the part and print—in this case, Don Corwin of Buell Automatics—revealed the backstory, including the part’s history, intended usage, and current manufacturing status.
Improving workplace ergonomics pays dividends by minimizing operator fatigue and providing more time devoted to completing the task at hand. That’s especially true with hand grinding operations such as deburring and eliminating welding seams. It also stands to reason that a grinding wheel is easier to use because it’s removing material efficiently and retaining its abrasive qualities longer.
Although the new Norton Quantum3 (NQ3) depressed center grinding wheel from Saint-Gobain Abrasives has additional features as well, I found it interesting that operator comfort was listed as one of its primary attributes. This is accomplished, the company says, by using a proprietary grain along with a tougher bond system containing a unique combination of fillers and bonding agents that allow for much better mix quality in manufacturing. As a result, the wheel provides substantially faster grinding for more metal removal and longer tool life with less operator fatigue, at the same time significantly increasing grinding output. In fact, tests conducted against competitive wheels indicated that NQ3 removed almost twice the amount of carbon steel at 5-minute intervals.
The new wheels are offered in 12 Type 27 all-purpose grinding application SKUs, one Type 28 all-purpose and two Type 27 SKUs for foundry applications. Sizes range from 4" × ¼" × 3/8", to 9" × ¼" to 7/8". Watch this video of the NQ3 in action in addition to downloading a white paper and product brochure, and read this article about Norton’s efforts to enable gear manufacturers to grind large, high-quality gears directly from a blank.
The DWS 250-4 vertical center for turning shaft-type parts is one of the Rasoma machine tools now available through the GMTA.
It’s always interesting to encounter equipment brands with which I am not familiar while visiting machine shops. Whether the machining center was built in Europe, Asia or elsewhere, it seems to signify a growing openness among machine shop owners to consider products built by OEMs from around the world. One such line is Rasoma, a company launched nearly a century ago and headquartered in Döbeln, Germany, that is now represented throughout North America by German Machine Tools of America (GMTA).
Used primarily for gear making, Rasoma machining centers primarily target the automotive powertrain, off-highway and other high-performance markets. The line includes vertical turning centers, four-axis shaft turning centers, end machining, double spindle and various special purpose machining centers with full automation.
Rasoma machines for gear milling, hobbing and shaping are available in a variety of configurations. According to the company, they offer high rigidity due to separate X and Z slides. In addition, the machine head is designed as a monoblock with polymer concrete fill. Thermal stability is enhanced by cooled motor spindles, and rapid traverse rates range to 60 m/min. at high acceleration, with feed and removal speeds ranging to 120 m/min.—less than 6 sec. from part to part, and turret indexing typically under 1 sec.
GMTA is a supplier of gear making, laser and finishing machines and systems with locations in the United States and Mexico. Watch this video of heavy crankshaft machining on a Rasoma FZS-3200 modular manufacturing center. Also, consider Techspex a resource in your search for the right machine tool for your particular application.
Heidenhain has added new cycles and features to its TNC 640 high performance mill-turn control such as enhanced graphics, interpolation turning and gear hobbing capabilities.
While making shop visits I’ve noticed that most programmers and operators tend to prefer a particular make of machine control over others. Devotees of the Heidenhain TNC 640 contouring control for mill-turn machines will be pleased to learn of new features now available on this unit, in particular one that allows for hobbing external cylindrical and helical gear teeth.
Known as Cycle 880, this machining process is performed through synchronization of the tool and lathe spindles. The cycle positions the rotary axis to the required tilting position and performs the infeed movements to the workpiece in the radial direction, and the milling movements in the axial direction.
The latest version of the TNC 640 also includes a new graphics package with a CAD viewer that opens any *.Step, *.Iges and/or *.Dxf file and allows an operator to evaluate the workpiece at the control. In addition, a new interpolation turning feature is available that is especially well suited for manufacturing large, rotationally-symmetric sealing surfaces, the company says, and for machining the housings of components of power plant technology in energy generation applications.
The TNC 640’s new graphics package includes a CAD viewer that opens any *.Step, *.Iges and *.Dxf file and allows an operator to evaluate the workpiece at the control.
Machine tool builders will appreciate the optional Dynamic Collision Monitoring (DCM), for which Heidenhain created a M3D converter. This is a PC tool with which CAD files of components in the machining envelope can be merged, edited and added to the collision monitoring program. Watch a video of the TNC 640 here. Also consider making an appointment to visit the company’s five-axis machining lab in Schaumburg, Illinois, which features a new machining center equipped with the TNC 640 control.
The Haas Minimum Quantity Lubrication (MQL) system allows machine tool operators to drill holes, tap holes, cut molds and machine metal with little or no coolant by delivering a steady flow of compressed air and small quantity of cutting oil directly to the cutting tool or tap. This reduces heat, removes chips and provides lubrication—not much oil, but just the right amount to be effective. This extends tool life, the company says, and in some cases eliminates the requirement for coolant during milling operations. The system’s key features include:
An oil reservoir, spray nozzle and pressure-gage regulator
A needle atomizer valve located at the tip of the Automatic Air Gun (the AAG is required in conjunction with the MQL system)
The amount of oil delivered is set by the air-pressure regulator on the reservoir
The air supplied to the reservoir comes from the main air manifold on the machine
The system does not need a separate air line
The AAG air line is connected to the MQL reservoir
Recommended air pressure is between 40/60 psi (2.7/4.1 bar), depending on the type of oil
Haas lists benefits including reduced chip welding, improved part quality, a cleaner machine both inside and out, and chips that are dry and ready to be recycled. In some applications the company says that MQL eliminates the requirement for flood coolant.