Tech Tips from Vollmer

While many industry segments use tools manufactured from HSS, carbide, and PCD, tools for surgical applications and orthopedics are often manufactured from stainless steel because when surgeons are drilling, grinding, or shaving bone and cartilage, carbide tools can break or create excessive heat. Surgical tools are generally manufactured from 17-4PH, 420, 440A, or 455 stainless steel, or M2 tool steel with lengths 50mm to 250mm and diameters 0.3mm to 12mm. However, small diameters and a stainless grade likely to deflect during machining can make precision production a challenge.

1. Steady rest & run-out

The innovative steady rest on the VGrind 340S supports the tool, preventing deflection during grinding, most critical in producing cutting tools to a standard beyond rival machines. Surgeons’ hand tools typically operate at high speeds, exacerbating the run-out impact of cutting tools. Run-out can reduce accuracy and even generate excess heat if a tool’s rubbing against a bone instead of cutting. Run-out up to 5mm is common in tools not precisely manufactured with a supporting steady rest. Excessive run-out generates excessive heat and diminishes precision where and when it’s needed most.

The steady rest on the VGrind 340S provides support under the tool to prevent deflection and a finger over the tool body support to eliminate movement. However, VOLLMER took the innovation a step further, providing two steady rest points to support the cutting flutes and the cutting tip of the tool. With typical tool shank diameters for hand tools being 4.5mm and the cutting flutes often much smaller, the potential for deflection grows with decreasing tool diameters.

To eliminate deflection, VOLLMER also introduced automated tool run-out compensation. Integrated into the NUMROTO control software, the run-out compensation cycle uses a measuring probe on tools in multiple positions around the tool diameter and re-calibrates the program to accommodate and eliminate any tool deviations caused by deflection.

2. Automation

OEM recipients specifying medical and surgical tools often require high production volumes of 5,000-off, so the VGrind 340S is supported by the HP160 automated tool loading system accommodating up to 900 tools with medical-standard 4.5mm diameter shanks. Manufacturers can also set the machine to run multiple programs sequentially without manual intervention. If a company needs to run a batch of 50 3-flute tools, then 500 2-flute tools of different diameters and geometry followed by other tool variants, the VGrind 340S can easily accommodate for unmanned operation, reduced costs, and around-the-clock production.

3. Flexibility

VGrind 340S is the only machine to incorporate multi-level machining with two spindles located on its A-axis. Feeding this innovation is a grinding wheel package accommodating up to 8-wheel sets so the VGrind 340S can automatically change from a flute grinding wheel to a gashing wheel, cup wheel, a 1A1 wheel for relief, O.D. grinding, or any other type of wheel.

This enables the VGrind 340S to produce cutting tools with zero manual intervention. In-process grinding wheel probing and automated wheel dressing can achieve long periods of precision lights-out production – regardless of the multiple tool types required. The flexibility of the VGrind 340S is complemented by next-generation V@DISON IoT digital solutions and the NUMROTO tool grinding software to enable customers to stretch their imagination with cutting tool design.