Sequential Broaching is becoming popular among manufacturers that want to make metal products with perfect finishing. And in Michigan, such demand for broaching services is growing. In this regard, any service provider worth their salt in this region needs to be well versed in the process—this article focuses on what you need to know about sequential broaching.
Broaching, as you may know, is a process that uses a cutting tool to remove material and the broaching tool (broach) produces circular or flat surfaces. A rod-like cutting tool has teeth arranged in sequential order. Each tooth exceeds the one before it in size- shapes are different too. The arrangement allows teeth to cut, one after the other. Each cut is bigger and better than the preceding one.
Sequential broaching is the process that takes an object through several shaping passes that happen in one stroke.
Properties of Broaching Materials
These properties are necessary for the sequential broaches- the cutting edges themselves.
- High level of sturdiness to withstand cutting forces
- Good conductors of heat
- Proper Coating to resist wear
How a Sequential Broach Works
Sequential broaching is an elaborate process. A few things should be in consideration before the cutting tool is ready to work. Here are the required steps.
- Selection of the broach cutting tool itself.
- Fixing the cutting tool on the broaching machine.
- Fastening the piece that requires shaping onto the machine.
- Setting the device to the necessary conditions.
- Starting the shaping process on the machine.
The broaching machine must meet the requirement of the work that it needs to do. Anyone wishing to work with it must base its selection on the material and its size. Also, it would be good to make a decision basing on the types of broaching machines that are available for collection.
Types of Broaches
Broaching adds a perfect finishing to the desired shapes of objects. Since the quality of products is critical to manufacturers, broaching has become unavoidable. There are different types of broaches that most manufacturers use for various purposes:
- Internal Broaching: Internal broaching is a process of shaping through holes. The holes do not need to be circular- they could range from keyways to gears.
- External Broaching: External broaching tools need fixing through holders. Holders keep them in position before they can operate.
- Ordinary-cut type broaches: These broaches have their teeth increasing in height from one tooth to the other. The arrangement allows them to remove materials in thin layers.
- Progressive Type Broaches: They have their teeth arranged in a manner that each tooth is wider than the one before it.
Some Sequential Broaching Problems and Possible Solutions
Manufacturers must be able to detect common problems in Sequential Broaching and they should also understand that there are suitable ways of solving these issues. Here are some of the issues and their possible solutions:
- Unreliable cooling properties. Solving this problem requires using only the recommended coolant. Besides, maintaining its cleanliness is critical. Further, preventing leakage of hydraulic oil into the coolant is necessary. Hydraulic oil may act as a contaminant to the coolant fluid.
- They damaged broach teeth. Massive face grinding is an essential process in remodeling the teeth. Fixing the broach in the right manner to the holder may help in protecting them from damage. To achieve this, the use of proper holders is paramount. The holders should be able to position the teeth. Correct teeth positioning creates an optimal cutting angle.
- The power supply must be intact at all times. Interruptions or insufficient supply may limit the operation capacity of the machine.
- Sharpening the cutting edges from time to time helps to maintain the capacity of the machine.
What Causes Wear in Broaches and Broach Machines
The sequential broaching machine may wear out due to constant friction, high temperature, and pressure. Wear affects the functionality of the tool. Sometimes it leads to its failure or breakdown.
Wear can affect the broach tooth. It creates a “cavity” on the tooth that eats out the cutting edge. If this continues over time, the tooth weakens. The good thing is that it is not difficult to control wear.
Causes of Wear
- Chemical decomposition of contact surfaces
- Contact with hard work material
- Deformation of cutting edge
- Cutting temperature speeds the wear-out process. That is why the coolant is critical in controlling temperatures.
Controlling Broach Wear
- Adjust the cutting speed to optimal levels (not too high).
- Coating the materials making the broach teeth. Coating provides resistance against high temperatures.
- Adjusting the shear angles of the tool reduces cutting temperature thus reducing wear.
How to Control Heating
The frictional force is the primary generator of heat. Energy generated by the cutting broach creates friction. The friction force turn generates heat (internal friction). Chips form as the tool cuts slide against the surface. The flakes create a frictional force from the outside.
To control the heating process:
Use a cooling lubricant reduces friction. The coolant also protects against rusting, reduces the wearing process on the tool, and washes away chips. Check the coolant and replace the cooling fluid to prevent contamination. Coolant removes heat by transferring it and reducing friction.
There is an option of using water or oil as the coolant fluid. Water reduces the process temperature faster than oil. The wrong side of the water is:
- It speeds up rusting which leads to wear of the machine.
- Water dries up quickly- its effects only last before it dries.
- The lubrication ability of water is lower than oil.
Some Advantages of Sequential Broaching
- The process finishes the shaping operation in one cycle.
- It produces high-quality surfaces.
- The process is fast and supports mass production.
- It increases the rate of material removal
- It is simple to design, make and run a broaching machine
Disadvantages of Sequential Broaching
- It is not productive on hard materials.
- The quality of products goes down in case the broach gets damaged.
- The process is not worth the investment unless producing in mass.
- The same broach cannot work on all material since it needs to match the size and shape, among other factors.