Keyway Slot Cutter
When manufacturers want to attach a gear, pulley hub, or coupling to the shafts of driving equipment, they generally use a keyway locking method. With this method, a key blocks shaft rotation and helps transfer torque. For this to work, different types of keyway cutting options are used to make a keyway in the shaft and coupling hub. This article will examine the most popular keyway cutting technologies used today.
Get Started with the Hansford Davis Keyseater
The Roughing Cutter The cutter most used and abused, while cutting key way slots, is the” roughing cutter” It’s not too big, I call these roughing cutters “beavers”. The beavers knaw out 97% of the key way slot so, the “fancy finishing cutter” can be slipped in the. With better heat and wear resistance than high-speed steel, these cobalt steel keyseat cutters can run at higher speeds and provide better performance on hard material. They mill precise notches in rotary shafts to fit machine keys and can also be used for slot milling. Keyseat End Mills Made of solid carbide, these cutters are harder, stronger, and more wear resistant than high-speed steel and cobalt steel for the longest life and best finish on hard material. They mill precise notches in rotary shafts to fit machine keys and can also be used for slot milling.
1. Keyseating (for Large & Specialty Keyways)
For about the same cost as machining a keyway off-site, you can purchase a CLIMAX Key Mill. These two-axis and three-axis mills cut keyways, slots, pockets, or flats on shaft diameters of 1.5 to 24 inches (38 to 610 mm). They can be operated in any position, thanks to their sealed gear box lubrication. Keyway Broach Set 30pcs HSS Keyway Cutting Tool for Lathe Inch Sizes 1/8B, 3/16B, 1/4C, 3/8C, 5/16C Broaches with 18pcs Bushings and 7pcs Shims price $ 52. HHIP 2006-1026 1/4 Inch C HSS Keyway Broach with 1 Shim 7. HHIP Single Flute Countersinks and Sets (Various Sizes: 1/4'.
Keyway cutting with a keyseater machine (or internal keyway slotting machine) removes material through a series of tooth cutting strokes. Some keyseaters only feature a single tooth cutter, while other machines (like the Davis Keyseater) use a multiple tooth cutter to achieve cutting speeds as fast as broaching.
Here’s how it works: The cutter on the keyseater slowly advances outward with each consecutive cut. This subtle movement allows each stroke to remove a little bit more material. The process repeats until the cut is deep enough to meet the specifications of the coupling hub print drawing.
The primary benefit of keyseating is that it offers great flexibility for large and specialty keyways. Custom sized tooth cutters are easy to obtain, and can also be quickly modified at an onsite tool room to meet unique specifications. However, depending on the type of your machine and cutting tool, keyseating may require a longer cycle time than traditional broaching. To get an idea of cycle time, view our chart that illustrates keyseater cutting times for various keyways and materials.
2. Keyway Broaching (for Speed)
Keyway cutting with a broaching machine is similar to keyseating. However, it’s more common for a broaching machine to feature a cutter with multiple teeth. Again, the cutter on the broaching machine is pushed through a hub and removes more material with each tooth the further it advances. Due to the multiple teeth, more material can be removed faster. Keyway broaching can usually cut a keyway in 1-3 strokes.
One important characteristic to note is that broach cutting teeth, like other cutting tools, need to be sharpened when dulled. For more information on this, read our article on broach sharpening. Another characteristic is that broaching machines can be aligned horizontally or vertically to push or pull a broach through a part.
One problem with broaching is the upfront cost of the broaches. They can cost up to tens of thousands of dollars and will require regular maintenance. Another issue is time. If a custom broach isn’t readily available, it can take weeks to months to manufacture the broach.
3. Wire EDM (for Small, Specialty Runs)
Keyway cutting with wire EDM (electric discharge machining) is generally used for small quantity runs that require precision or other specific cutting options. Tool and die builders use wire EDM to remove material through a method that might be described as “shock” or “evaporation.” In this method, a spooling copper wire is brought up close to cut a target with electrical sparks (but doesn’t directly touch the component).
If you’re looking for speed, wire EDM is probably not your best keyway cutting option. A standard machine might operate at 12 square inches per hour. As an example, if your part is 6” thick, a wire EDM machine will cut 2” deep per hour. However, one redeeming factor to this is that wire EDM machines can run without an active operator. With that said, some applications best suited for wire EDM include: prototype parts, rush orders, and one-off requests.
4. Shaping (for Blind Keyways)
Shaping is a good option for cutting blind keyways. “Blind” refers to keyways that don’t go through the entire length of the part. Some of the above keyway cutting options, such as broaching and wire EDM, aren’t designed to handle blind keyways.
As with some keyseaters, shaping uses a single tooth cutting tool. Unlike keyseaters, shapers aren’t guided down through the cut on a fixed post. As a result, shaper cuts can’t achieve the same level of accuracy as keyseater cuts due to unguided deflection. This increases the need for proper tolerance inspection.
In order to cut blind keyways, shapers require users to pre-cut a “relief” at the end of the soon-to-be cut keyway. The relief allows metal chips to break. They can be formed by cutting an internal groove on the inside diameter for hubs or by pre-drilling a hole.
5. Milling (for Shaft-Only Keyways)
Much like shaping, milling allows users to cut partial length, tapered, or straight keyways. Milling is popular for cutting external shaft keyways. However, milling inside diameter keyways on hubs isn’t common because the other side of the coupling gets in the way (with traditional straight milling techniques). But if needed, an internal hub keyway could be milled with a special 90º angular milling head.
Like shaping, quality is an important factor to consider when milling keyways (due to lack of unguided cuts). Tolerances, such as corner radius quality, need special attention in order to ensure correct spec. Otherwise, problems could arise such as an imbalance to the power transmission system or a key that doesn’t fit.
Ready to Start Keyway Cutting?
Keyway Slot Cutters
We hope this guide has given you a clearer understanding of your keyway cutting options. If you’re ready to start keyway cutting, or looking for a way to reduce cycle time and manufacturing cost on your current keyway cutting process, contact us. During our conversation we can discuss which keyway cutting option is best for your application.
Introduction: How to Broach a Keyway
Keys are an important part of mechanisms. They provide a solid and reliable interface between shafts and a wide variety of other objects including pulleys (as in my case), sprockets, levers and gears. There are a variety of different types of keys, but the simplest and most common is the straight key.
For this project, I'll be broaching keyways in some pulleys that I'm in the process of machining (still need to finish up the OD). The material is 6061 aluminum, it's 3/8' thick with a ø3/8' hole and I'll be broaching a 3/32' keyway.
Step 1: Tools and Materials
Tools:
Broach Kit, including a broach, shims (as needed) and the appropriate bushing.
Keyway Slot Cutter Tools
Arbor or Hydraulic Pres
Materials:
Cutting Oil, my favorite is Tap Magic
Step 2: Setting Up
This is a small broach in soft material, so I can easily use the 3 ton arbor press. If you're broaching a tougher material and/or a larger broach, you'll need a hydraulic press, as large broaches can require thousands of pound of pressure to cut. Also, larger broaches are much longer and often do not fit in an arbor press.
For this setup, I've selected the ø3/8' bushing, and the 3/32' broach. They should fit together well, sliding easily without any slop. Since the keyway is so small, I will not be needing any shims, which are used with larger broaches.
Insert the bushing into the hole you wish to broach. It should drop in easily. Next, rotate the slot to where you wish to cut the key. Liberally lube up the broach with your favorite cutting oil and and insert the broach into the slot in the bushing. The first quarter or so should slid in easily before the teeth engage with the part.
Step 3: Broaching
Align the part with the gap in the press and ensure the broach is straight up and down. Then apply even pressure, ensuring that the part is not tilting or rocking off the arbor press work surface. In aluminum it requires little effort. Be prepared to catch the broach as it reaches the end of its stroke- it may fall out. If the broach remains stuck in the part, use a small punch or piece of stock to press it all the way out. Do not strike the broach, as you can mushroom the end (sometimes imperceptibly) and cause yourself a big headache. Only press a broach.
Step 4: Resetting & Test Fitting
With the broach removed, use a chip brush to remove the swarf from the broach. It's important to clean these chips before broaching another keyway. Failure to do so can result in the broach jamming in the bore.
Carbide Keyway Cutter
Now, we can take a key and test fit the freshly broached pulley with a shaft. It's a perfect fit. Often times I purchased shafts that already have the keyway machined in them. They are available from McMaster Carr.
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