Tools for CNC Cutting and Shaping of Thermoplastics
Machining thermoplastics like PVC, ABS, acrylic and polypropylene is a lot like working with wood in that, there can be so much variation between batches from different vendors that it is virtually impossible to come up with optimized feeds and speeds that will work in all situations.
On the positive side, there are usually enough similarities between different lots of the same type of thermoplastic that general purpose guidelines can be found to get you started. However, for those of us who want to squeeze the last drop of performance out of our CNC routers, nothing beats chasing down the "perfect" combination of RPM and feed rate(chipload) whenever we embark on a new project. To that end, we developed the "Sweetspot Test". It really works and repays the time you spend by reducing bit breakage, improving cut quality and increasing the productivity of you cutting operation.
What are depth rings?
What are depth rings and what tools can have them?
Depth setting rings are plastic collars that are securely pressed onto the 1/8 in. shank of a drill bit, end-mill, router bit, or similar rotary cutter. There is no charge to add the rings, but the user is cautioned to make sure that their equipment is compatible with their use.
Most PreciseBits 1/8 in. shank bits are available with or without depth setting rings. Bits that can't have rings are:
- End-mills smaller than 0.005" (0.127mm)
- Shanks longer than 1.50" OAL
- Cutting depths or necks longer than 0.50"
- SRD kerf cutters (MM5D8)
How do they work and why would I want them?
The shank side of the ring (top side in the picture to the right) is accurately positioned (d ±0.004 in.) relative to the tip of the tool. If the shank-side of the ring is pressed against the collet when the tool is loaded, the tip of the bit will be a known distance (d) from the face of the collet. Knowing this distance, the programmer can plunge the tool, confident that the depth of cut will be as expected and will remain the same no matter how many times the tool is changed. If all of the tools in the programmer's magazine have been fitted with depth setting rings, an automatic tool changer can load and unload tools with the tip of each one the same distance from the face of the collet.
This is especially helpful with micro-tools where "touching-off" on some reference surface to calibrate the tool height can damage or break the tip of the tool. Rings also find widespread use in inlay pocket cutting where relatively large diameter cutters are used to "hog out" basic shapes, followed by much smaller diameter finishing bits that clean up the edges, sharpen the corners and add fine detail to the finished part.
LPKF and T-Tech
The most common value for d is 0.800 in. (industry standard). However, with the advent of mechanically etching printed circuit boards in the mid 1970s, a new standard was implemented for the special purpose tools developed for this application.
Today, only machines made by LPKF and T-Tech adhere to this special standard. Systems from AccurateCNC, MITS, Sun and EverPrecision are compatible with the original industry standard depth of 0.800 in.
Tool Family: MM202
Deep cutting, 1/2 inch shank upcut end-mills optimized for shaping the sheet goods commonly used in the manufacture of dimensional signage, furniture and cabinetry. The flute geometry has been tuned to insure smooth cutting and low deflection under high chip loads.
Designed to work together, the fish tail bit is a high-performance roughing tool while the bull-nose and ball cutters are intended for clean-up and fine surface finishing. All of the bits can be used as stand-alone cutters for single pass, high-speed cutting and shaping .
Tool Family: MM204
Deep cutting end-mills optimized for shaping the sheet goods commonly used in the manufacture of dimensional signage, including HDU and PVC. The flute geometry has been tuned to insure smooth cutting and low deflection under high chip loads.
Designed to work together, the fish tail bit is a high-performance roughing tool while the bull-nose and ball cutters are intended for clean-up and fine surface finishing. All of the bits can be used as stand-alone cutters for single pass, high-speed cutting and shaping .
Tool Family: MP104
The "O" flute geometry introduced more than a decade ago is one of the most efficient flute designs for cutting thermoplastics that has yet been invented. With a high rake angle and relatively low helix, O-flute cutters manage to cut acrylic, polycarbonate, ABS, PVC and a host of other sheet polymers at very high chiploads without raising a burr or fracturing the edges of the kerf. All of this while leaving a remarkably clean surface finish. The real surprise is that this revolutionary geometry also works incredibly well in wood and aluminum.
Tool Families: EM2D8, EM2E8 & EM2E4
Designed specifically for the dimensional signage and egraving markets, 2-flute solid-carbide "V" cutters feature polished, high-rake cutting edges capable of producing a surface finish suitable for edge-lit transparent signs and plaques. Edge finishes are typically smooth and free of chatter.
High flute volume and precisely shaped ejection paths support high chiploads in a wide variety of sign making substrates. Precise "V" angle formation (±0.2°) permits either single-pass or multi-pass cutting without fear of steps or streaks.
Tool Families: CM204, CM304, CM404
The 1/4 in. shank with 1.00 in. depth of cut (DOC, CM304 and CM404) are designed for deep machining in large format dimensional signage as well as very detailed carving of architectural components, back-lit lithophanes and other decorative items.
Although the geometry of these tools was optimized for cutting and shaping hardwoods, they are equally at home machining plastics, phenolic composites, unfired ceramics and aluminum.
Tool Family: MM3316
3-flute deep cutting end-mills designed for cutting thermoplastics used in packaging and thermoforming. The flute geometry has been tuned to insure smooth cutting and low deflection under high chip loads.
Standard Length
This tool family combines large flute volumes and high-shear flute geometries to produce clean, chatter-free cuts in most thermoplastics with little, or no, melting of the swarf. High feed-rates at moderate RPM (12K - 40K) offer significant productivity gains over conventional tooling.
Tool Families: MP103 & MP108
Optimized for high-speed cutting of thermoplastics, the very high rake angle and large flute volume make this the perfect cutter for virtually all thermoplastics, even polycarbonate (Lexan®). These tools are particularly useful for cutting plastics with low melting temperatureswhen using CNC routers with limited RPM and/or feed rate controls.
These tools excel at cutting materials that tend to fray or chip during machining.
Tool Family: MM208
High-rake 2-flute cutters optimized for cutting and shaping most soft plastics, especially high temperature materials that do not melt when being cut with moderate chip loads. The flute geometry supports relatively high chip-loads and efficient swarf extraction.
Tool Family: MM208
The 1/8 in. dia. shank tools in this series have been optimized for single-pass and cleanup cutting in high resolution 3D carving applications where straight side walls are required.
Tool families: DC208, DC2M8
Like all of our cutters, PreciseBIT PCB drills are made using the finest grade submicrograin carbide. Sizes ranging from 0.008 in. (0.2mm) to 0.250 in. (6.35mm) are available from stock. Diameters down to 0.001 in. (25 micron) are available upon request. Slotting drills and high aspect ratio tools are available on a special order basis.
Tool family: EM4E8
4-flute tools designed to produce chatter-free counter sunk holes with no edge fraying in G10, carbon fiber and phenolic substrates. The cutting edge geometry generates virtually zero lifting forces making the tools compatible with thin sheet goods.
Designed by a corrosion chemist to:
· dissolve varnish and gummy deposits in the spindle bore
· loosen rust
· inhibit corrosion
in spindle bores and on collets and toolholders.
An effective solution for removing fuzz, fray, hair and splinters from 3D carvings and engravings in wood, composites and plastics. FuzzBrush is lightweight and comfortable to use.