5 Major Benefits of the High Precision (HP) Head for Multi-Spindle Screw MachinesLeave a Comment
Davenport Machine’s High Precision (HP) Head is specially designed to replace the standard revolving 8-SA head. ABEC 9 angular contact radial bearings now replace the standard bronze bushings, significantly improving spindle stiffness and rigidity. This advanced design allows the HP Head to run with more precision and accuracy. In fact, the HP Head provides index repeatability to within 0.0006 inches.
The new design — now standard on the Davenport HP and Hybrid Machine — offers a range of unique benefits which ensure optimal performance for all Davenport machines.
Key Advantages of Our HP Heads
Running duplicate layouts of the same part on a machine equipped with an HP Head versus one running an 8-SA head, the HP Head will hold tolerances 30-50% tighter than a brand new 8-SA head. In addition, the increased spindle rigidity allows for wider and more accurate form tools, eliminating, in many cases, the need for a shave tool and freeing up a valuable tool position. The HP Head also allows for improved part diameter accuracy.
2. Thermal Stability
The HP Head will only produce 1/3 of the temperature rise from room temperature at any given spindle speed. A machine with an 8-SA head running at 135°F, will run temperatures around 92°F at the same RPM with the HP Head. For most parts, this also means that no tooling adjustments need to be made as the machine “warms up” or “cools down” during morning start-ups and stock-ups. Most parts run on an HP Head have almost no size changes due to temperature. Lubricant temperatures stay lower, which allows for more effective cooling of tools, as well as extended lube life. Lower running temperatures also help keep the shop floor temperatures more stable and comfortable.
3. Increased Spindle Rigidity
The Outer Spindles of an HP Head are directly supported by 5 Super Precision Angular Contact Ball Bearings. The bearings, in an arrangement similar to what you find on most of today’s single spindle CNC Lathes, are rigidly mounted directly into the Revolving Head, not in bolt-on housings. These heavy pre-load bearings have ZERO play, compared to the .0015-.0020 clearance in the bronze bushing of a new 8-SA head. As a result, part accuracy and repeatability are more similar to a CNC Lathe than a traditional Davenport Multi Spindle. Additionally, 50% wider form tools can be used and surface finishes are generally improved 30%. Many parts that previously could only be run on 6 and 8 spindle machines can now run on 5 spindles with substantially shorter cycle times.
4. Long Life Span
The Angular Contact Ball Bearings of the HP spindles are rated to last 16+ years in a typical application. These bearings will maintain almost new accuracy for 95% of their service life, until they ultimately lose their pre-load and need replacement.
All 5 spindles are constantly lubricated by an advanced air-oil lube system that pressurizes each bearing cavity, maintaining a flow of clean, cool, lubricated air through each bearing. This is achieved while providing back-pressure to each bearing seal to keep chips and contaminants out.
Lastly, the OD of the HP Head is treated with a low-friction, micro-textured hard coating that significantly reduces wear not only on the Head OD, but also on the mating bore of the machine bed. After 15 years of service, the first four machines equipped with HP heads have seen no measurable wear on the Head OD or machine bed bore. Uncoated heads typically see the head gap wear open .001 to .003 larger than the “new” condition during that time frame, and may require expensive machine re-builds to continue making high quality parts.
5. Lower Maintenance/Operational Costs
Higher accuracy and thermal stability leads to better production efficiencies. With a conservative 5% increase in productivity, the HP Head can put out an estimated additional 100 hours – or $5,000 – of production each year, based on a $50.00/hr machine cost.
Additionally, the HP spindle ball bearings last roughly 16x longer than the 8-SA’s bronze boxes and thrust bearings. The average annual maintenance cost of an 8-SA Head, including parts, labor, and lost production hours, is approximately $2,250. HP heads have an estimated 16-year maintenance interval, with an annual amortized cost of just $344.
Machines equipped with HP Heads use approximately 40% less lube oil. On a machine running 2,000 hrs per year, that’s approximately 22 gallons less per year, or an annualized savings of around $112.00.
With over a hundred years of experience in advanced machine technology, Davenport Machine is proud to offer some of the most innovative, long-lasting solutions on the market. Along with our other cutting-edge products, the HP Head is designed to help you streamline your processes, while reducing costs and improving productivity.
To learn more about our product offerings, we invite you to browse our comprehensive library of technical literature. For more information on our HP Head specifically, check out our FAQ guide