Process
Knurl cutting is a subtractive manufacturing process. It involves removing material from a workpiece to create the desired knurled pattern. This is typically done using a knurling tool that has sharp, hardened edges. As the tool rotates against the workpiece, it cuts into the material, forming ridges and grooves.

Tooling
Knurl cutting tools have teeth or serrations that cut into the material. These teeth come in various patterns and sizes, allowing for customization of the knurling design. The tool's sharp edges bite into the workpiece, displacing material to create the knurled texture.

Applications
Knurl cutting is ideal for materials that are harder and less malleable, such as stainless steel and hardened alloys. It is commonly employed in high-production environments where speed and efficiency are crucial.
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Advantages

• Precise control over knurling depth and pattern
• Suitable for a wide range of materials
• Easily customizable for specific applications

Disadvantages

• Generates more waste material
• May require higher machining forces
• Produces more noise and vibration

Cutting Type Knurling tools create a knurling pattern by material removal. The Cutting Knurling Process is performed when the knurling tool holds the knurling wheel with a lead angle that creates a sharp cutting edge.
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The Knurl Cutting Tool is engineered to reduce the pressure exerted onto the work piece and minimize stress to the spindle of the lathe during the operation. The Cutting Style Tool is the best for knurling any material, including hard and large size work pieces as well as, for thin wall tubing.

The performance of the Dorian Tool Knurl Cutting Tool is up to 20 times faster than a conventional Knurl Forming Tool.

Process
Knurl forming, on the other hand, is a non-cutting or deformation process. It involves pressing or rolling a knurling tool against the workpiece's surface, displacing the material to create the knurled pattern. No material is removed during this process.

Tooling
Knurl forming tools have a smooth surface with the desired knurling pattern engraved onto them. These tools apply pressure to the workpiece, causing the material to deform and create the knurled texture. They are typically used in specialized knurling machines.

Applications
Knurl forming is often used when the material being worked on is soft or easily deformable. It is suitable for materials like plastics, brass, aluminum, and mild steel. Knurl cutting is also preferred when precise control over the knurling pattern and depth is required.
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Advantages

• Minimal material waste as no material is removed
• Less force and energy required
• Suitable for hard and brittle materials

Disadvantages

• Limited control over knurling depth and pattern
• Not as customizable as knurl cutting
• Specialized machinery may be required

editors note: This article covers some of the questions that have been asked as a result of of previous article we posted: KNURL CUTTING VS KNURL FORMING

As seen at IMTS 2022. ​Dorian Tool’s Jet-StreamTM Thru Coolant Cutting Tools use a patented thru-coolant locking clamp which is precisely aimed to direct high pressure, high velocity coolant exactly onto the cutting edge of the carbide insert, from a short distance of 1⁄4”.

This controlled Jet-Stream coolant, directed onto the insert chip interface (right under the chip and over the insert cutting edge) will dissipate the generated heat very effectively as well as lubricate the cutting edge of the insert, causing the chips to hydroplane over the insert surface instead of adhering to it. As a result, the insert will operate at a constant low temperature, with a clean and undamaged cutting edge, changing the way metal is cut.

Higher speeds and feeds can be achieved, with a better surface finish, tolerance control and machining performance.
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The insert life is extended up to 200%.

It's that time of year for IMTS!

​Here's a preview of some of the products that are going to be featured during the International Manufacturing Technology Show September 12-17.  You can see all of these new products and talk to the manufacturers in the Tooling & Workholding Systems Pavilion in the West Building Level 3. 

Supermini Set. Horn USA is featuring the Supermini tool holder system with face clamping as a set, in response to customer requests for different tooling system heights. With this holder variant, clamping is not carried out via the lateral surface of the cutting insert but via a clamping wedge on the face. This results in a greater holding force on the insert and thus high rigidity of the entire system. This increases repeatability when changing the insert and provides better utilization of the available space. This is a big time saver on Swiss-type lathes, as the user can change the cutting insert without removing the tool holder.

New carbide grades for system DAH8 - Horn USA is expanding its range of carbide grades for its DAH milling system to enable its use for machining a wider range of materials. The new grades SC6A and IG6B complement the tool system for high-feed milling. The SC6A grade is suitable for machining the ISO M material group, as well as ISO S materials as a secondary application. Horn has developed the IG6B grade for machining the ISO P group, while it is also suitable as a multipurpose grade for other material groups.

If you would like to learn more about any of these products or to see a demonstration, get in contact with us and we'll set up some time with you to visit your shop!

Dorian Tool has some very detailed technical information in their Solution Tool catalog to address deep hole boring. First we're going to list the fundamental rules of selecting the correct boring bar and then take a deeper dive into the fundamentals of troubleshooting. 

If you want more information, technical specifications and much more detailed information on troubleshooting you can download the Solution Tool catalog below.

There is sometimes confusion over the difference between Knurl Cutting and Knurl Forming and what is the best application to use for each method.  Here's a quick synopsis of the differences and ideal application solutions. 

For a Cutting Knurl, the knurl wheel’s axis is rotated to provide a leading edge, where the sharp edge will cut the knurl pattern into the work piece. Additionally, with a Cutting Knurl, less pressure is required for the operation and higher speeds and feeds can be used (use the same cutting data of High Speed or Cobalt turning tools). When Knurl Cutting, use full faced knurl wheels with a sharp edge, to penetrate into the work piece and cut the knurl pattern.

In Forming Knurl, the knurl wheels axis is set parallel to the work piece axis, and forced against the work piece, displacing the material to form the knurl pattern. A large amount of pressure is required to displace the material that forms the knurl pattern. When Knurl Forming, use beveled edge wheels to protect the edge from chipping which will create a smooth surface finish.

Double Tracking means that the knurling wheels are not tracking properly. In this situation, the knurling wheels will create a different pattern than the original design and may overlap or "double die"

There are two main causes of a knurling tool double tracking: 

1. The knurl wheel isn’t set deep enough into the workpiece.  Dorian Tool recommends increasing the depth. The knurl depth should always equal 35% of the knurl pitch.
2. The circumference of the work piece blank is not a multiple of the knurl pitch. To correct this, you must change the before-knurl diameter of the part or select a knurl wheel with a different pitch.

Dorian Tool  has developed a “Knurling Calculator Spreadsheet” that can calculate all of the parameters to avoid double tracking.

If you would like to request an electronic copy send us a note in the comments section below or, for faster results, in the form you get when you click the button below.  We'll quickly get a spreadsheet sent over to you!

Tech Tips: Dorian Tool

The lathe is one of the oldest and most versatile machine tools. Few shops can do without the processing capability offered by the CNC lathe. Long before automatic toolchangers were applied to milling machines, the lathe had a multiple-tool configuration. The tool post gave lathe users the ability to select from several mounted tools and index them as needed during a turning cycle.

Many CNC lathes are still offered with the manual tool post design. Shops can generally purchase these machines at very reasonable prices. Some shops have found a need to increase the flexibility of these lathes by adding an indexable turret in place of the manual tool post.

Installing such a turret can give a real productivity boost for shops running on Colchester, Harrison, Nardini, Bridgeport, Southwest Industries and other popular combination CNC lathes. With a CNC turret, more tools can be carried at one time. Programming the turret brings the right tool into the cut at the right time automatically. No stopping the machine to index a manually operated tool post is needed so cycle times are reduced for applications that use more than one tool.

For many turning applications a manual tool post has sufficient capacity. But any shop that is looking for a through-put gain in their turning operation without a major investment in new machine tools, can benefit by considering installation of a CNC turret.

The issue is more about processing efficiency than tool capacity, says lathe accessory maker, Dorian Tool (East Bernard, Texas). A turret configuration allows the machine tool to carry tools mounted in operation sequence. Sometimes turret tool capacity is sufficient for more than one job to run without a tooling setup in between. But significant production time is saved by the ability to automatically index the tool turret as part of the lathe's part processing program.

The turret offered by Dorian Tool is a bi-directional unit. Indexing therefore takes the shortest part from one tool station to another. It's operated by a three-phase 220/380 volt 50/60 hertz electric motor through an anti-backlash gear drive. Tool position is controlled by an absolute encoder which tracks actual position of the tool station. The working position of the turret can be right or left hand depending on the unit location ahead of or behind the lathe's spindle axis.

A proximity switch detects tool position and verifies turret lockup before a go signal is sent to the CNC. A three-piece Hirth-type coupling is used to hold the clamped turret radially. The turret indexes, station-to-station under one second. Fast index is achieved by not lifting the turret face. The entire indexing mechanism is housed in a Meehanite grade casting that helps damp cutting induced vibrations.

Four standard sizes of turrets are available. They are 100, 120, 160 and 200 mm respectively. Toolholding capacities of eight or 12 stations are available in ID, OD or combined tooling configurations.

Tool capacities range from 12 to 32 mm (1/2 to 1-1/4 inches). A VDI turret disk is available. Both turret disks have an integral coolant delivery system.

Simple electrical and coolant connections easily interface with the lathe. If an indexable turret is the difference between a CNC lathe and a CNC turning center, then this accessory is a cost effective way to up-grade your lathes.

Tech Tip: Dorian Tool