One tool, one set-up
When the previous supplier pulled out, the customer had only one option: to find a partner who would not simply copy what already existed, but would rethink the application. For EMCO Gears, a family-run company with deep roots in precision, motorsport and high technology, this was precisely the incentive. Together with tool partner HORN USA, a modern manufacturing approach was developed for a demanding bevel gear set with an unusual geometry. Design, tooling, five-axis machining and metrology are seamlessly integrated – and show how gears can be manufactured efficiently, reproducibly and with future-proof technology.
EMCO Gears is a family-owned and operated manufacturer with two locations: engineering and manufacturing in Elk Grove Village, Illinois, and a second location in Indianapolis, Illinois, which supports racing services and sales. EMCO serves the motorsport, defence, aerospace and industrial sectors with a common focus: the supply of highly engineered parts where material selection, heat treatment and manufacturing strategy are as important as the design specification. For this application, EMCO was asked to manufacture a bevel gear set for a customer whose previous supplier had stopped producing the parts. EMCO agreed on one condition: The gear set was to be manufactured using a modern approach.
A 60-degree bevel gear set
The gear set is used in a PTO (power take-off) assembly. Typically, bevel gear applications have a 90-degree power transmission, but this project required a 60-degree design. This difference affects the gear geometry, contact ratio and the manufacturing process required to achieve these goals.
Changes in the profile, position or stability of the gear set elements quickly become noticeable in the form of noise, heat, wear or premature failure. With a very small margin for error, repeatability is critical.
The gear is manufactured from SAE 9310/14NiCrMo 13-4 (1.6657), a steel alloy with a high nickel and chromium content offering good strength and hardenability. After case hardening, the gear develops a hardened surface while the core remains tough. This provides a combination of surface strength and underlying toughness suitable for demanding duty cycles.
Beyond the limits of traditional bevel gear processes
Once the cutter diameter is selected, development can often be restricted by that specific tool. EMCO had a different goal. The team wanted the freedom to design the required tooth form and then produce it on a five-axis machine with a tool that cuts both sides of the tooth profile in one pass. The resulting solution is based on a bevel gear milling tool specifically developed for EMCO's five-axis strategy. "In the past," says Wolfe, "four special tools had to be used. We can now achieve the tooth profile with just one special tool." Implementation was quick, as HORN was already familiar with EMCO's spindle interface on the DMG five-axis machine. For the indexable inserts, HORN started with a proven profile shape and modified the profile to obtain the required cutting edge.
The workflow at EMCO combines design, production and measurement. The team mills the gears, checks the topography on a Zeiss CMM and updates the program if necessary. The advantage of this is that dimensional adjustments to the teeth can be made without changing tools.
From 8 hours to 15 minutes
Before the HORN milling cutter was introduced, helical gears were produced with small end mills and conservative cutting parameters, with the machining of a single gear taking around 8 hours of machine time. With the new process, milling the teeth now only takes around 15 minutes, followed by metrology and any necessary program updates. Wolfe emphasises that the implementation depends on realistic starting parameters. He describes the cutting data recommended by HORN as practical and accurate, which supports stable production.
Slot broaching system in operation
In addition to bevel gear cutting, EMCO focused on slot broaching. To ensure a continuous process flow, EMCO integrated the broaching onto the lathe using the HORN N117 system. Wolfe describes the new process: "Instead of waiting for a batch to be completed, the parts are passed from turning to subsequent operations with a more consistent flow. A custom insert is used. We wanted special corner radii for greater strength and HORN adapted the cutting edge profile accordingly."
Both Wolfe and Bruce Williams, Product Development Manager at EMCO, describe the collaboration with HORN as solution-oriented and responsive. Wolfe points to the quick communication between the sales contact and technical support, which helped clarify tool design details rapidly. Williams explained that while EMCO can define how a part should be machined, the benefit lies in having a tooling partner that can translate a particular requirement into a timely, usable solution. The result is a clear competitive advantage, allowing EMCO to bring the finished product to market faster.
Positive outcome
By combining five-axis manufacturing, Zeiss-based topography measurement, surface metrology and HORN's product portfolio, EMCO has a process for manufacturing bevel gears that was faster to develop, easier to operate and better aligned with actual production requirements. For EMCO, it means improved gear meshing, quieter operation, longer life and easier manufacturing, while meeting cost targets in a changing market.