Kerfing refers to an application which utilizes saw blades, in multiple passes, to achieve numerous thin grooves in material. This process was traditionally used for the purpose of bending material by removing stock from one side of the panel or solid wood. For example, stair companies generally use veneered plywood to produce curved risers by kerfing out the back side of plywood to allow it to bend into a radius.
Image 1A — shows the kerfed material, which will be bent and placed under the stair tred.
More recently, kerfing has become popular in acoustic panel production on CNC routers
Image 1B — shows an example of small V-grooves in the panels which are applied to walls and ceilings of building interiors to affect sound properties and provide sound dampening benefits. The acoustic panels also provide ascetic benefits, which make cut quality extremely important.
These and many other grooving applications on panel products are being performed on CNC routers, but often with limited production efficiency. There are several ways to optimize kerfing applications to achieve greater production efficiency.
Strategies to improve efficiency and cycle time:
Use multiple blades: A simple solution to improve cycle time can be achieved by using multiple blades in one assembly to cut in one pass. This strategy has been used for years on moulders and rip saws, but more recently has become popular on CNC routers. Many operations have utilized a moulder aggregate, which allows multiple blades to be stacked onto an arbor, which can be installed into any 3 axis spindle with C — axis. Other companies have opted to purchase 5 axis CNC routers which allows blades to be installed on arbors and run in a horizontal orientation on the 5 axis spindle.
Image 2A — shows an example of a moulder aggregate which provides greater flexibly and enhanced performance to a 3 axis
CNC router.
Image 2B — shows multiple blades stacked on 1 tool holder to be run on a
5 Axis CNC router. This simple solution creates dramatic increase in output on
one machine and allows sheet stock to be machined with greater accuracy.
Use diamond tooling: One of the greatest challenges associated with carbide saw blades is, frequent sharpening and the requirement to disassemble the tooling stacks for service procedures. Assembly and disassembly does increase the chance for inaccuracy and imbalance of tooling. Improper sharpening can also be problematic and cause accuracy and balance issues. Diamond saw blades provide a better alternative for saw stacks on CNC routers, and eliminates the concerns described above. Dramatically extended tool life of diamond saws eliminates the need for frequent tool changes and reduces the margin of error substantially. Diamond saw sharpening procedures are more accurate and ensure optimal balance and accuracy. Many of the materials being machined are often relatively abrasive which makes diamond saw blades a logical tooling choice.
Important cautions: As we strive to improve processes and increase machinery output, it is obviously critical to consider the safety restrictions of machinery and operator competency, as large tool assemblies do require special attention.
Tool size It is critical to research the allowable tool length and diameter of saw blade as machine limitations vary drastically. The size of the tool will obviously be a critical consideration when performing tool changes,
and during cutting applications. It is imperative that the diameter of the tooling is large enough to project into the material without interfering with other machine components, but not too large to exceed the max diameter of the machine. Length of tool assembly is also crucial to ensure safe operation of machine and spindle.
Tool weight Weight of tool assemblies can be provided by your tooling supplier in the design phase of any project, prior to manufacturing any tooling solution. It is imperative that spindle weights are respected to ensure optimal long term performance and safety. To comply with restrictions, it is possible to add weight reduction laser slots to saw blades and make all spacers with aircraft grade aluminum. Machine and spindle manufactures can advise on the specific limitations for each machine, but always consider that 3 axis machine limitations can be different from 5 axis machine specifications.
Dynamic balancing Required balancing standards can be determined by the size of tooling, and running RPM of the spindle. Industry standard requires G2.5 specification, but overbalancing in these situations is never a bad idea. Saw blade assemblies can improve machine efficiency dramatically, but the risk of spindle wear must be considered as well as overall safety of the assembly. Due to horsepower constraints, most CNC routers must be run a higher RPM than standard saw applications. Most machines require RPM of 8000 to 12000, which is not an issue for router tooling, but larger saw blade diameters at 8 to 14 inch require special consideration when running on a CNC router. Saw blades are generally balanced to 3000 to 6000 RPM for standard saw equipment which is sufficient for standard sawing operations. However, a saw blade assembly such as the one shown in image 2B, must be balanced to much higher RPM and will require additional balancing procedures to ensure safe operation.
If kerfing is an application which can benefit your operation, take some time to consider all the options currently available with new machinery and tooling solutions. Multiple
saw assemblies have added a great deal of versatility to
CNC routers and can be a critical tool to optimize performance and increase output of production lines.
