HSD Spindle Repair

HSD Spindles are the most common type of spindle we repair. The cost of repair is usually less than the cost for a cartridge replacement. Also, the end result of a rebuild will have better vibration. Some HSD spindles have a critical speed below 24,000 rpm. Most HSD spindles will have a different level of vibration at 18,000 vs 24,000 rpm because of the critical speed. If the spindle is balanced at 24,000, the level of vibration at 18,000 will be higher and vice versa. It is good practice to balance the spindle at the highest operating speed for each particular customer.

Free Inspection: Spindles sent to HS Spindles are inspected for free.

Firm Quotes: All quotes provided are firm quotes. The exception to our firm quote policy is a motor winding failure which can occur unexpectedly. Expedite options available.

Warranty: All spindles have a six month warranty. The cost of bearing replacement is not covered. All warranty labor is free. See HSD’s warranty at bottom of page.

Below are Examples of Common Repair Issues

HSD’s have balance screws in two places, at each end of the rotor. These reside directly under the stator windings. These screws can come loose over time and rub against the windings. The spindle will continue to operate until the screw is ground to dust or the windings are damaged. If not caught in time, it can lead to an expensive stator rewind. If your spindle has a sudden rise in vibration or noise, it can be due to a screw coming loose.

Also, note the fretting corrosion on the bearing support. This is due to looseness and lack of anti-seize. The cylindrical fits are inspected and repaired to eliminate fretting and unnecessary heat build up.

HSD spindles have a drawbar end that looks like this. Over time the drawbar can wear out the guide bushing. This will open up the clearance for the guide and the vibration will increase exponentially. Some newer spindles have been found to have no lubrication from the factory. Eventually the drawbar rides off center and begins to pop during a tool change. Vibration will drastically increase and destroy the rear bearings. Also, as it worsens the sensors will lose the presence of the drawbar and may come in contact with the drawbar. This reading failure will cause PLC error codes.

This drawbar was pulled from a spindle less than two years old. Looks like there is no lube from the factory. The corrosion and lack of lubrication will wear these parts out fast. The biggest indicator will be high vibration in the rear of the spindle and a erratic tool change function. The longer it is operated like this, the more damage caused. The only way to fix this is to chrome plate the drawbar or replace it. We manufacture HSD drawbars, currently for the ES919 and 988A.

This is typical of HSD drawbars. They will wear on the spring seat. Eventually the sticking and popping take a toll on the gripper threads and will break the threads off at the thread relief on the end of the drawbar. This is can a very dangerous failure as a tool may come flying out at high operating speed. We sell new drawbars made out of heat treated alloy steel.

This is the rear of a 789 spindle, one of the nicer HSD models on the market. This unit comes with an encoder and this makes the repair more difficult. HSD issues warnings not to have the cartridge repaired, but to be replaced. We have successfully repaired many of these with no issues. The 789 is on our list of spindles to reverse reverse engineer and offer a replacement. Stay tuned for more updates on this. Normally, we can reverse engineer a spindle for about 75% of the cost of a replacement. It will be made in America and have much better customer support.

We repair manual tool change spindles as well. Customers are given teh option of steel or ceramic ball bearings . We use GMN bearings made in Germany with ABEC 7 precision. Spindles have a 6 month warranty with the same coverage provided by HSD. An excerpt from HSD’s manual is below.

We repair all makes and models. 915, 919, 929, 988, 789 and the newer versions with the new type of sensors.

Directly from HSD’s Manual1.12 Guarantee Conditions

HSD S.p.A. guarantees that the electrospindle has been inspected at its plant with a positive result.

Works under warranty shall be performed free at the HSD S.p.A. facilities, transport at the customers expense; HSD S.p.A. shall not be liable for termination of production during the warranty period.

The warranty does not cover faults due to normal wear of those parts which, by their nature, are subject to rapid and continuous wear (e.g. gaskets, belts, bearings, etc.). in particular, HSD S.p.A. gives no guarantee as to the working life of the bearings, as this depends on various factors including: the degree of balancing of the tools, the types of machining operation, collisions and / or mechanical stresses beyond the values indicated by the manufacturer.

HSD parts manufactured by HS Spindles below:


Spindle Repair Form

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HS Spindles Repair Procedure