HAIMER GMBH, the manufacturer of tool holders, dynamic balancing machines, heat shrinkers and accessories, conducted an internal case study on the benefits of using a tool balance balancing machine at its own production site. The company found that it was different depending on the processing center. Each machining center can save 20,000 to 40,000 dollars per year. By balancing the inserted tool and the shank, the spindle life can be doubled, the cutting volume is increased by 10%, and the tool life is extended by 10%. Surface quality and accuracy are improved, and flutter and waste are reduced. Simultaneously. the experiment shows. Balance tools produce positive results in any speed (r/min) range, and high-speed machines, especially those with spindle speeds greater than 8000 r/min, benefit the most from balanced tools.
Mr. Michael Layne, product manager at Hoffman in the US, said in a white paper: "A well-balanced handle with an imbalance of only 1.0gm-mm" will produce 0.56 pounds (about 2.49 Newtons) at 15,000 rpm. Radial force on the cutting technology website. When studying the tool holder and its balance requirements, we found that the average initial imbalance of the CAT-50 holder is 250 gm-mm. At a speed of 15,000 r/min, 250 gm-mm Unbalance will produce up to 140 pounds (about 623 Newtons, the cutting technology website note) continuous radial force!". The name of the white paper is "Detecting and Correcting the Imbalance of Tool Holders in High-Speed ​​Machining," written by Layne for its company, Hoffman, a manufacturer of precision balancing machines in the United States.
Layne says that due to the movement of the cutting tool, the tool imbalance can cause vibration and surface ripple. High frequency flutter can also cause poor surface finish. Imbalances can also keep tight tolerances. Thereby increasing the scrap rate.
On machine tools, unbalance can cause premature failure of the spindle bearings, resulting in costly downtime. Recent studies by several major toolholder manufacturers have shown that with a balanced tool holder and tool, tool life can be extended by as much as 50%. The tool, holder and stop knob (if applicable) should be balanced as a component. However, not all tools need to be balanced. Each tool in a process should be evaluated to determine if the application needs to adjust tight tolerance balance. Tool speed (r/min), tool weight, tool operation and stress applied to the spindle should be considered.
The cause of the imbalance may come from inherent factors. Features including the shank may also come from random causes such as the position of the collet or the position of the collet screw, or the cutting tool, or the set screw used on the end mill shank. Unbalance from inherent factors is usually solved by the tool holder manufacturer through design and pre-balancing. Random causes may change each time the cutting tool is changed or when the chuck is loosened and tightened. There are no handles for moving parts. For example, a heat shrinkable shank, when it is pre-balanced, often does not easily lose its equilibrium state. The hydraulic chuck is also easy to balance and it is easy to regain balance during use.
Regardless of the spindle speed and toolholder type used, the internals of the balanced toolholder and tooling reduce costs and maintain tight tolerances and other benefits that come with a quick return on investment.
Tooling in 10 seconds Rego-Fix Tool has developed a simple and fast method for loading tools in less than 10 seconds, both heat-shrinkable and mechanical.
This tool holder company is suitable for powerRgrip tool clamping systems with high-performance, high-speed machining and registered trademarks. powerRgrip is a mechanical clamping system. Rego-Fix says it continues to have a stronger clamping force than a heat-shrinkable tool holder.
The system is designed to be compact; that is, a unique, tight hydraulic device that accurately and safely mounts the tool into the collet and then inserts the collet into the shank. The benchtop hydraulic design is designed to apply an accurate pressure – up to 6 tons – to press the collet and tool into the shank. Hydraulics can also be used to remove tools, chucks and holders. The tool is clamped to a keyless design that relies on the center force of the shank to hold the tool in place.
The system even provides a tool clamping system with higher accuracy and precision, and can clamp tools with a diameter of 0.20mm to 20mm (0.0787402" - 0.7874016") in the same holder. And unlike heat-shrinkable clamping devices, there are restrictions on small knives.
Andreas weber, president of Rego-Fix Tool, said the company's recent tooling for micro-drilling and milling machines enabled the powRgrip to use clamping diameters as small as 0.20 mm.
The table to the right shows the tolerances for the holders of various sizes.
| Shank diameter | tolerance | ||
|---|---|---|---|
| Metric (mm) | Imperial (inches) | Metric (mm) | Imperial (inches) |
| 6 to 10 | 0.236～0.394 | -0.009 | -0.00035 |
| 10~18 | 0.394～0.709 | -0.011 | -0.00043 |
| 18~30 | 0.709~1.181 | -0.013 | -0.00051 |
| 30~50 | 1.181~1.968 | -0.016 | -0.00063 |
The powRgrip guarantees a runout of less than 3μm (0.0001181 inches), which the company claims can maintain tight tolerances even after 20,000 tool changes. and. The pre-adjustment tool of this system is less than 10μm (0.0003937 inches).
Weber said: "The system has the highest clamping force and jitter accuracy compared to any other tool clamping system," he added, adding that the system's hydraulic clamping force provides high dynamic damping capability during cutting. .
In addition to its mechanical properties, Wober says the powRgrip system also controls the temperature of the pre-set tool to be accessible, without waiting for heat loss after presetting, as in a heat shrink system.
Rego-Fix demonstrated its powRgrip system at the Eastec trade show in West Springfield, Massachusetts on May 22-24.
The advantages of the heat shrink technology of the recommended shank of the heat shrinkable tool: the clamping force and concentricity are improved, and this technique is very popular among mechanics.
The theoretical clamping pressure of the hot press table technology is a function of the interference fit between the hole and the shank and the wall thickness of the shank. This is a formula derived from Lames theory. Due to the difference in Poisson's ratio between the two materials, the clamping pressure of the carbide shank is about 10% lower than that of the same size steel cutter.
Pulling force is a function of clamping pressure, coefficient of friction, and contact surface area. A typical calculation uses a coefficient of friction of 0.15, which assumes a surface finish of 12-16 microinches on the inside diameter (ID) of the shank and a surface finish of 8 microinches on the shank. Command Tooling Systems used a steel-steel that was both 16-a-inch polished and tested to confirm the calculated values. This shows that the drawing force required for the surface polished carbide tool is lower than the value calculated by the friction coefficient of 0.15. Pulling force is proportional to the coefficient of friction. Experience has further proved that ultra-finished carbide shanks on high-screw knives will come out under strong cutting or tremor conditions. Therefore, the shank should be polished below 16 microinches for optimum retention.
The handle should be round, not flat. No engraving, pits or other surface defects.
It is necessary to wash the parts that are compatible with each other. It is recommended to use a non-flammable solvent as a cleaning agent. During the heating process, the oil will turn into sludge, and it is easy to "stick" the parts together. Care should be taken to avoid storing moisture in the back of the cutting tool, as the expanding gas may generate high pressure when the tool is removed.
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