END USER: Hommer Tool and Manufacturing Inc., (847) 394-3355, www.hommer.com.
CHALLENGE: Increase complexity of ground parts while maintaining tight tolerances.
SOLUTION: CNC cylindrical grinding machines.
SOLUTION PROVIDER: United Grinding North America Inc., (937) 859-1975, www.grinding.com.
Hommer Tool and Manufacturing Inc. literally centers its operation on precision and quality. The company’s 24,000-sq.-ft. Arlington Heights, Ill., facility is laid out in a hub-and-spoke arrangement that puts QC in the center of its 11 machining departments. This strategy, along with a transition from manual to automatic OD grinding, has helped the manufacturer of custom mold-ready components succeed.
When James “JR” Hommer Jr. assumed responsibility for the company 15 years ago, its business model was to manufacture simple, round components for the injection-molding market, but customers were beginning to ask for more complex parts. Because its CNC OD grinding was basic, the company could only make pieces up to 1 " (25.4mm) in diameter and 12 " (279.4mm) long.
“My first major move was to hire a marketing manager,” Hommer said. “Then, out of the blue, I received a promotional mailer from a manufacturer of automated grinding machines, which put that kind of machine on my radar.”
After researching the available options, Hommer opted for the Studer line of cylindrical grinders from United Grinding North America Inc., Miamisburg, Ohio. Today, Hommer’s OD grinding department consists of five Studer machines: two S40s, an S31, a basic S33 and an S33 with B axis.
The S40 machine offers a grinding length up to 63 " (1,600mm) and a fast direct drive of the infinite B-axis, a functionality that has created new business opportunities for the shop.
James “JR” Hommer Jr. (left) and Operations Manager Rick Frankowitch with a Studer S33 grinding machine.
The Studer grinders enabled Hommer to change its focus from manufacturing commodity parts to larger, more complex parts, while commonly achieving tolerances as tight as 0.0002 "(5.1µm). Coupled with an increase in communications with customers, this capability helped Hommer triple its business, finding its niche as a provider of cavity components, custom cores, rotating cores, custom core pins, thin-wall ejector sleeves and stack-up tooling, according to the company.
The shop creates the components out of various materials, including tool steels, such as S-7, H-13, D-2, M-2 and 420, copper and beryllium copper. Most of its components range from 0.25 " (6.35mm) to 3 " (76.2mm) in diameter. The bulk of Hommer’s pieces require an average of 15 operations, beginning with soft-state chipmaking operations, including cutting off, gundrilling, turning and milling. After heat treating, the parts can undergo centerless grinding, OD and ID grinding, form grinding, surface grinding, honing, hard turning, hard milling and wire and sinker EDMing.
As business grew, the company added a new Studer about every 2 years. “I initially selected Studer because the programming was the same across all machines,” Hommer said. “That’s a huge benefit to us because our lot sizes are small, averaging around 32 pieces, and our cycle times are around 3 to 5 minutes. We do about four changeovers per shift, and the simple setup and mechanical processes on the Studers allow us to set up in a half hour or less.”
The department’s capacity is about 350 hours per week and includes two shifts, which complete more than 2,000 unique details per year. According to the company, 93 percent of Hommer’s jobs involve parts the company has never made before and most likely will never make again.
“One advantage we have over companies just now entering the market for complex, custom parts is that we have invested in these machines over time and have the skilled labor to operate them,” Hommer said. “It would be very difficult for a shop to invest in all of this equipment at once.”
Operations Manager Rick Frankowitch explained that customers hold Hommer to an extremely high standard and don’t want any variability in the tool.
Because these customers need to guarantee that their molds can produce millions of parts, Hommer can’t deviate when it comes to quality. Hommer is often more expensive than the competition, but customers are willing to pay the higher price because the company says it consistently produces parts that are true to the print specifications.
“I had a customer pay our company the ultimate compliment,” Frankowitch said. “He said he wastes a lot of time checking perfect parts.”
Related Glossary Terms
- centerless grinding
centerless grinding
Grinding operation in which the workpiece rests on a knife-edge support, rotates through contact with a regulating or feed wheel and is ground by a grinding wheel. This method allows grinding long, thin parts without steady rests; also lessens taper problems. Opposite of cylindrical grinding. See cylindrical grinding; grinding.
- centers
centers
Cone-shaped pins that support a workpiece by one or two ends during machining. The centers fit into holes drilled in the workpiece ends. Centers that turn with the workpiece are called “live” centers; those that do not are called “dead” centers.
- computer numerical control ( CNC)
computer numerical control ( CNC)
Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.
- cylindrical grinding
cylindrical grinding
Grinding operation in which the workpiece is rotated around a fixed axis while the grinding wheel is fed into the outside surface in controlled relation to the axis of rotation. The workpiece is usually cylindrical, but it may be tapered or curvilinear in profile. See centerless grinding; grinding.
- gang cutting ( milling)
gang cutting ( milling)
Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.
- grinding
grinding
Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.
- grinding machine
grinding machine
Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.
- gundrilling
gundrilling
Drilling process using a self-guiding tool to produce deep, precise holes. High-pressure coolant is fed to the cutting area, usually through the gundrill’s shank.
- hard turning
hard turning
Single-point cutting of a workpiece that has a hardness value higher than 45 HRC.
- inner diameter ( ID)
inner diameter ( ID)
Dimension that defines the inside diameter of a cavity or hole. See OD, outer diameter.
- milling
milling
Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.
- outer diameter ( OD)
outer diameter ( OD)
Dimension that defines the exterior diameter of a cylindrical or round part. See ID, inner diameter.
- surface grinding
surface grinding
Machining of a flat, angled or contoured surface by passing a workpiece beneath a grinding wheel in a plane parallel to the grinding wheel spindle. See grinding.
- tool steels
tool steels
Group of alloy steels which, after proper heat treatment, provide the combination of properties required for cutting tool and die applications. The American Iron and Steel Institute divides tool steels into six major categories: water hardening, shock resisting, cold work, hot work, special purpose and high speed.
- turning
turning
Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.
Author
Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.
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