Spindle Repair Glossary

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	Angular Contact Bearings - Preloading bearings is the process of removing the internal clearance of the bearing by applying a permanent thrust load. This applied force makes the rolling elements run in a single “track” and it removes any axial play in the bearing assembly. Read More...
	Ball Cage - Ball cages are used in machine tool spindles to allow the shaft to grow toward the rear of the spindle during thermal expansion. The rear bearing compliment rides inside the ball cage which enables them to move in an axial direction while capturing them in a radial direction. Read More...
	Bearing Failure - Determining the cause of failure for a spindle is much like a CSI investigation. Northland Tool & Electronics gathers as much information as possible from our customers including machine history, manufacturing process, estimated loads, coolant usage, noise heard, surface finish and a spindle history. Read More...
	BIG-Plus Taper - BIG-Plus® is a patented spindle system that provides dual contact between the spindle face and the flange face of BIG-Plus® tooling. Simply by switching holders, you can greatly increase tool rigidity, reduce runout and add significant productivity to your machining applications. Read More...
	Ceramic Vs. Steel Bearings - Ceramic bearings have become more popular over the last 15 years. There are many reasons for their increased use over steel. Perhaps the greatest benefit of ceramic bearings is that they weigh considerably less. Read More...
	Component Balancing - Component Balancing is the first step in the spindle balancing procedure. Northand Tool & Electronics uses several types of balancing equipment for component balancing. We start by balancing the spindle shaft without its external parts. Read More...
	Coolant Jacket - Coolant jackets are used in machine tool spindles to carry chilled coolant that holds the spindle temperature at a constant. This eliminates tolerance changes due to thermal expansion. It also removes the heat generated by the stator in motorized spindles. Read More...

	Draw Bar Assembly - The spindle drawbar assembly is used to retain the tool in the spindle shaft. Every spindle with a drawbar system has specifications for drawbar force that must be met. Read More...
	Draw Bar Wear - This drawbar has reached the end of its expected cycle lifespan. The groves you see are from the Belleville washers wearing the shaft during the drawbar compression cycle of the tool change. Read More...
	End Play - End play is the act of the spindle shaft moving in an axial direction. Excessive end play in a spindle is usually an indication that the spindle condition is deteriorating. It is generally caused by looseness in the bearing assembly. Read More...
	Grind Plate Grind - A Grind Plate Grind is used to bring non-conforming shaft and housing bearing journals, tool interfaces (cat tapers, HSK, pilots, etc) and/or any other surface that has a very tight tolerance requirements back to its original specifications. Read More...
	Improper Clamping - Improper clamping of spindle housings causes bearing noise, vibration, inability to hold fine surface finish and premature bearing failure. Read More...
	Inpro Seal - Inpro seals are found in several models of machine tool spindles. Usually they can be seen on the front of the spindle where the shaft exits the housing although there are several applications and configurations. They offer very good protection from bearing contamination. Read More...
	Lubrication of Spindles - Spindle bearings are lubricated to reduce wear and friction. A very thin layer of lubricant sits between the moving elements separating them from each other. If this film is not sufficient enough to properly lubricate the bearing premature failure will occur. Read More...
	Micron - Definition: a metric unit of length equal to one millionth of a meter. Why is this important to know? The tolerance we use for bearing fits is measured on the micron scale. When we repair your spindle it is important to make sure your spindle meets or exceeds these specifications or the spindle repair could suffer premature failure. Read More...
	Oil Seal - Oil seals are a common way to reduce bearing contamination in machine tool spindle applications. They are used primarily in low speed applications because they make contact with the rotating shaft and have a limiting surface feet per minute specification. They do eventually wear down. Read More...
	Preload of angular contact ball bearings - Preloading bearings is the process of removing the internal clearance of the bearing by applying a permanent thrust load. This applied force makes the rolling elements run in a single “track” and it removes any axial play in the bearing assembly. Read More...
	Rotor - The rotor is the non-stationary part of the electric 3 phase induction motor system found in a spindle. It is part of the spindle shaft. It rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the... Read More
	Rotory Union - The rotary union of a spindle is mounted to the rear of the shaft and it permits the movement of liquid from a stationary point into the rotating shaft. Typically rotary unions are used for the transfer of coolant in through tool coolant applications. Read More
	Rotory Union Ceramic Disc Type - Ceramic disc type rotary unions are used in machine tool spindle applications of various makes, models and applications. This is a typical set up where one end mounts to the drawbar and one end mounts to the machine. Read More
	Roller Bearings - Roller bearings are used in spindle applications that require a high level of radial load capacity. Some examples of this are large centerless grinding spindles, Large low speed milling spindles and spindles that have radial loads from drive belts. Read More...
	Spindle Shaft - Follow the link to view an interactive breakdown of the different parts of a spindle shaft. The spindle used here is a Heald 405. Read More...
	Spindle Shaft Tool Change Capture - This piece is mounted to the rear of a GMN spindle. During tool change gripper fingers grab this piece and captivate the spindle shaft. This reduces the reverse loading to the spindle bearings and in theory increases bearing life. This particular piece came out of a GMN spindle repair that was done by one of our competitors. Read More...
	Stator - The stator is the stationary part of the electric 3 phase induction motor system found in a spindle. It can also be known as a field. The stator consists of wire windings that when energized create a magnetic field that pushes the rotor... Read More
	Thermistor - Thermistors are placed on or near the spindle stator to monitor the heat of the motor windings. The machine control monitors the outputs of the thermistor and if the outputs reach an overheat level the spindle is shut down. Read More...