Precision machining tools have been greatly improved by linear encoders in a number of ways. A linear encoder is a sensor, transducer or readhead paired with a scale that encodes position. It works by the sensor reading the scale and converting that encoded position into a digital signal which is then decoded into position by a digital readout. Linear encoders are used in metrology instruments and precision machining tools such as digital calipers and coordinate measuring machines. Linear encoders use many different physical properties to encode the position such as optical, magnetic, inductive, and capacitive.
Optical linear encoders are the most popular form of encoder on the market today especially for precision machining tools. A typical scale for optical linear encoders varies from hundreds of microns down to just a few. This form of scale is very accurate and precise which is why it dominates most of the market. The magnetic encoders are another favourite and they work by scales that are either active which is magnetized or passive which is reluctance.
There are two main applications for linear encoders including measurement and motion systems. Measurement is specifically important when it comes to precision machining because it needs to be accurate down to the hundredth of a millimeter. Linear encoders for measurement are commonly found in coordinate measuring machines (CMM), laser scanners, calipers, gear measurement, tension testers, and digital read outs. Motion systems from linear encoder also aid precision machining because they provide accurate high speed movement.
Linear encoders are either open or closed which can carry different advantages and disadvantages. Being open they are prone to dirt especially being in precision machining tools and machines. However enclosing the encoder limits it accuracy due to friction. The option of the encoder being closed or open in a machine needs to be thought about on a case by base basis.
Precision Machining achieved with Cold Forging?
It has been found and tested that precision cold forging creates perfectly shaped parts with simple or complex geometry and it’s quicker than machining. Precision machining is the most popular way of producing tools and parts for machinery but it is very costly due to the machines and the length of time it takes to create the parts. Forging can work on cold or hot materials; cold working is conducted at temperatures of at 480 degrees Celsius to 780, and hot working at above the recrystallisation temperature of the material being forged.
Normally applying strenuous and heavy deformation to cold steel cracks the steel but by maintaining compression at all points this does not occur. By using small components cold forging can create a final shape with stainless steel providing they are well lubricated and contained. Cold forging makes products precisely to their shape which cannot be achieved with hot forging, and since with cold forging components can often be formed in one blow production rates are very high. Cold forging is a great alternative to precision machining because it cuts the machining time quite considerably which for a company means lowers costs on producing parts and a faster rate at which they can be supplied.
Robert Cooke, chairman of a precision machining company, states that production time has been cut from 2 minutes to a few seconds. The timing and the process involved in cold forging is dependent on the material being used but generally there are 6 steps that take place, pre-form production, upsetting, annealing, lubrication, cold forging, and the finishing machining. Cold forging has many advantages over the traditional precision machining techniques including small batch sizes can be achieved using quick change tooling, monitoring the process of the methods for quality control, fine surface finish, high productivity, and so on and so on. With these dramatic advantages it is thought that cold forging will become even more popular amongst the precision machining industry over the years to come.