When you operate a cylindrical grinder, you need to use some type of workholding. There are different types of workholding systems. One of these is the chuck and collet system for cylindrical grinder.
In general, workholding involves the use of any device that can hold the object you are working on to the grinding machine. This can be a chuck, clamp, fixture, vise, and other devices.
The Chuck and Collet System
Sometimes, you may need to work on an object that is too tiny for center points. You may also have an object wherein you only need to profile or feature one end. In these cases, the type of workholding method you should do is the chuck and collet system.
Chucks and Collets
For any turning operation, the main workholding tools are the chucks and collets. Aside from these, you will also need the face driver and the mandrel. The chuck and collet each have their own features. Chucks may have either two, three, four, or six jaws that can hold an object.
Although most chucks are operated by hand, there are some models that you can use through automatic, electric or hydraulic means. Chucks also have various functions and accessories.
When you need to present several surfaces of an object to a machine, use an indexing chuck to turn it into different positions. If you need to do longer turning, use a tailstock to support the chuck. Meanwhile, if your object has an irregular shape, it is best to use a magnetic chuck.
When working on a smooth surface of a cylindrical or round bar, you need collets for a tight and accurate hold. Collets comes in different gripping sizes. Like chucks, collets have various functions, too.
For gripping hex and square shapes, you need a special collet. There are also collets for objects that comes in metric, decimal, as well as nonstandard measurements. Furthermore, you often use collets together with an automatic bar stock feeder.
How the Chuck and Collet System Works
The chuck and collet system of workholding is dynamic. In the workholding between centers system, your work setup must be fixed or stationary. But with the chuck and collet system, your object moves along with collet or chuck.
The four-jaw chuck method, in particular, is an accurate technique. Here, you can align with extreme precision the centerline of your workpiece with that of the chuck and spindle. You can place an indicator along the blank and tune initial runouts using the individual jaws.
With this system, you may need to spend more time in indicating and adjusting each part of the workpiece. But as a whole, you can load and unload this system faster than by using other methods.
For this, you will need to use an expandable collet insert as well as a tapered barrel. In any case, the set up and indication stages of this system are critical. It is also important for you to align and indicate the tapered barrel of the collet to the workhead’s centerline.
Aside from these, you should also focus on the general accuracy of the system. The accuracy of the chuck and collet system can reach up to four microns. But if you need to save time, you can work with two microns. Here, you will be working faster but with a lesser amount of precision.
Swarf contamination refers to any kind of wear in the spindle of the grinding wheel. It may also refer to wear in the bearing assemblies of the chuck or collet.
Even if your have a precise drive and software, swarf contamination can still affect your work. Some machinists may not be comfortable with the dynamic nature of the chuck and collet system.
To address their concerns, some manufacturers have come up with as stationary V-block fixture. This fixture is able to correct inaccuracies caused by the system.
How to Choose the Right Collet Chuck
There are steps that you should take in choosing the right collect chuck for your work. The first thing that you should do is to identify the spindle nose of the grinding machine where you will mount the chuck on. Make sure that the spindle nose follows the industry standards.
The second step involves determining the required capacity of the chuck. This will be based on the size of the work parts that it will hold. Make sure that the drawtube bore size of the machine match in the case of a bar feeding application.
After identifying the spindle nose and the capacity of the chuck, you can proceed to the third step. This involves the narrowing down of your choices depending on specific features as well as benefits.
These specific features include the dimensions of the external clearance and the dead-length versus pullback operation. They also include the requirements of the set-up time as well as the RPM capability of the chuck.
Once you are able to choose the right collet chuck, you will be able to operate with great efficiency and effectiveness. If the collet chuck meets your requirements, you are bound to have a smooth and problem-free time with your work.
For objects that are too small for center points, the chuck and collet system is the best method for you to use. Through this method you can shape and work on your object with ease.
The dynamic nature of this system will enable you to operate the machine with success. As with all other types of workholding systems, using the chuck and collet system for cylindrical grinder requires safety.
Don’t forget to wear the right working gear to protect your face as well as your body. Likewise, make sure that your working area is prepared for cases of fire and other emergencies.