FREQUENTLY ASKED QUESTIONS

1. What type of free shipping do you offer?
2. Why did my  air bearing spindle fail and What Does HST do to Repair It?
3. How long will it take to repair my spindle?
4. What is QTA?
5. What is GPG?
6. What is Kiss Grind?
7. How much will it cost to repair my spindle?
8. What is Forensic Engineering / Quality Assurance (FEQA)?
9. What is ISO 1940/1 G0.4.?
10. What is HST’s warranty?
11. What conditions void a warranty?
12. What can I do to increase my spindle life?

1. What Type of Free Shipping Does HST Offer

When requested, High Speed Technologies, Inc. will pay the cost to ship your spindle to our facility and back from any place  in the contingent United Sates. The following qualifiers apply:

• Spindles up to 50 lbs will ship UPS 3rd day
• Spindles up to 51 to 150 lbs will ship UPS ground
• Spindles over 150 lbs will be shipped common carrier
• Packaging and special handling charges are not included
• QTA orders will ship next day
• HST will apply a comparable credit for customers who want to handle their own shipping.
• HST reserves the right to pick up the spindle with our own vehicle for local customers.

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2. Why did my Air Bearing Spindle fail and what does HST do to repair it?

As you can imagine after 100,000 spindle repairs we have seen all types of failure. Different types of spindles fail for different reasons. None the less, very often spindle failures can be avoided. Outlined here are some common failure modes we have observed.  A variety of failures are displayed here. However, one should keep in mind that these failures are inter-linked. For instance a clogged orifice can result in a radial crash. Conversely, a crash can result in clogged orifices. Here we are simply trying to show our customers some of the problems we encounter and what we do about them.

• Clogged Orifices
• Coolant Leakage
• Radial Crashes
• Axial Crashes
• Burned Stators
• Bad Brushes and Holders
• Corrosion
• You Name It

Clogged Orifices

Minute orifices, some slightly larger than a human hair, meter air in and around the rotor providing “float”. Axial thrust bearings typically have the orifices drilled directly into the base material. The radial bearings often have removable brass jets with orifices drilled into them. When these orifices become clogged the lift can become unstable or lost completely.

Clearing all orifices and balancing the air flow is a critical component of air bearing repair. Unstable air flow can degrade a dicing saw cut. HST verifies proper flow through all orifices on every air bearing spindle we repair.

These Jets go to a Westwind Radial Bearing. They're sitting on a penny next to Mr. Lincoln. They are typical of many radial bearing jets. Often we can clear the orifices without removing the jets. However, when that is not possible, we press out the old jet and press in a new one.

Thrust bearings come in a variety of material; ceramic, brass and bronze being common. This hair and orifice drill are sitting on a reconditioned Disco Thrust Bearing. The orifices are drilled directly into the ceramic material. Proper surface finish and grooving are critical for "float."

For maximum air bearing life, clean dry air is a must. HST recommends individual sub-micron filters in close proximity to the spindle. When spindles are replaced, exceptional care must be taken to prevent contaminate ingression into the open line. Moisture can cause mineral deposits to develop in the orifices. Below are photos of actual jets from Disco Radial Bearings. They are magnified 200 X.

This jet orifice is almost completely clogged by some unknown particulate.	This photo shows crystalline growth that built up over some time and virtually choked off the orifice.	We don't know what this stuff is. But it doesn't look good and it shouldn't be there.

HST has various methods for clearing jets. However, when they become severely clogged we use proprietary methods to remove the radial bearing from the spindle housing and replace the jets.

Sometimes the crash causes the jet to become clogged. At HST, all orifices are cleared and checked.

Coolant Leakage

Proper coolant flow is critical for long spindle life. However, improper coolant can cause numerous problems and premature spindle failure. Trace amounts of chemicals can, overtime, attack the seals and cause them to leak. Electrolytes in the coolant can cause erosion through galvanic action. On the other hand DI water can aggressively leach certain metallic surfaces sufficient enough to erode seal areas. We recommend carefully adhering to the manufacturer’s recommendations. If these are not available, consider adding a minute amount of sodium carbonate or another non-halogen soluble salt to the water to abate any corrosion when using DI water. Chlorides, fluorides, iodides and bromides should be avoided. Also, keep the coolant pH neutral or slightly basic.

Cracked coolant jacket	This erosion ate completely through the coolant jacket.	Damaged coolant jackets are replaced with new.

It’s not uncommon for us to repair someone else’s repair with a damaged o-ring. O-rings need to be properly selected and sized. After that proper installation is a must to avoid minute leaks that can eventually cause more severe damage. We maintain a large inventory of the correct o-rings and our experts will install them properly. All o-rings are changed out on every repair and the spindle is pressure checked for leaks just to be sure.

Proper care and handling are required to prevent premature seal failure. O-rings must be carefully installed and compatible compounds selected. In both cases these leaking o-rings resulted in serious damage to the spindles.

Radial Crashes

As stated above radial crashes can be the result of a clogged orifice causing loss of lift. However, the most common cause is operator error such as programming an excessive feed rate or causing the spindle to run into something.  Hard radial crashes are the most difficult failures to repair.

Some examples of radial crashes. Radial crashes can gall the base metal and clog the jets. There are often other tell-tale signs that suggest the cause, i.e., contamination or overload.

A reconditioned radial bearing.

At HST we strive to restore the radial surfaces to original condition. Our precision grinding and resurfacing techniques help us meet that goal. When that is not enough we can remanufacture new parts. Our radial test loading conforms to OEM standards.

Axial Crashes

Like radial crashes, axial crashes can be the result of a clogged orifice causing loss of lift or operator error such as programming an excessive feed rate or causing the spindle to run into something.  Often axial and radial crashes accompany one another. HST employs a number of proprietary techniques when repairing axial bearing surfaces. A variety of materials are used for axial bearing surfaces including, ceramics, impregnated bronze, brass and plastics.

Some examples of axial crashes. Like radial crashes, axial crashes can gall the base material and clog the jets. These too, often leave other tell-tale signs that suggest the cause, i.e., contamination or overload. The bearing surface material can vary. At HST we repair them all.

HST repaired this impregnated bronze thrust bearing for a Westwind spindle used for optical manufacturing.

This is a ceramic thrust bearing used on Disco Dicing saws. It has been completely refurbished with new ceramic insert and refinished housing.

The thrust surfaces of this Disco spindle are precision ground and reshaped to match the OEM design.

Burned Stators

Dicing, drilling and routing spindles pack a lot of power into a small space. Without proper coolant they heat up in a hurry. It doesn’t take long for a high power-to-size ratio motor to reach a temperature where the winding insulation begins to break down. 

Insufficient coolant is only one potential problem. Other causes include loss of phase, improper voltage, overload and improper application. When properly set, most modern drives should protect spindle motors against such problems.  None the less, from time to time stators burn up. When they do HST can get you going again.

Burned stators are removed along with their cooling jacket. The stators are pressed out of the cooling jacket and re-wound.

Not just any motor repair shop can rewind spindle motors. Investment must be made in dies and forms to properly hold and shape the windings. Each stator type requires its’ own forms and dies. The stator laminates are especially thin to operate at the very high frequencies required.  Because of the thin laminates extra care is required when removing the old windings.

All stators are carefully examined and tested.

Bad Brushes and Holders

When brushes are not properly supported they can wear down quickly. This can result in poor spindle performance and fault trips. The carbon dust generated can contaminate clean room areas causing additional troubles.  HST custom manufactures high quality brush holders.  Our plastic brush holders have stainless steel inserts to prevent  stripped out  threads.

Rust and Corrosion

In most cases rust and corrosion are related to leaks. Other caused are related to humid air and condensation.  Corrosion can attack all non-stainless parts. 

Proper protection in shipping is a must to prevent corrosion damage due to condensation. All our spindles are shipped with desiccants and wrapped in Cortec Vapor Phase Corrosion Inhibitor  Mil-Spec B220119/020.  No matter what caused the corrosion or how bad it is , your spindle will shine when it leaves HST.

Damaged Tapers

When working with equipment that is dialed-in using a microscope it goes without saying that accuracy and smooth running is paramount.  If the taper is damaged or galled the dicing saw will vibrate, wobble or just perform poorly. 

The surface finish as well as the taper angle are critical for an accurate cut. At HST we are sticklers on the quality of our grinding.  Our Kellenburger  grinder  and skilled operators provides a precise finish and correct angle.

Other Things

Since 1986 (over 100,000 repairs ago) HST has encountered almost every imaginable problem. Some additional problems we see from time to time include the following:

• Broken Tips
• Damaged Connectors
• Shorted Wires
• Damaged Hall Effect Sensors (Brushless DC)
• Damaged Encoders

We repair all types of spindles used in semiconductor and printed circuit board manufacturing.

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3. How Long Will It Take to Repair My Spindle

Of course the time required to repair a spindle is somewhat dependent on the nature of the problem. That not withstanding HST has the fastest turnaround time in the industry. As soon as your spindle reaches our shop, it is in our Forensic Engineering Quality Assurance (FEQA) program. Serial numbers are checked against our data base of over 100,000 repairs. The spindle is broken down, cause of failure determined and a firm quote prepared within 24 hours. Typical non-GPG repairs take approximately 4-5 days after approval of quote. Spindles requiring GPG typically require 6-8 days for repair.  Got to get it back right away? Ask for our QTA service.

There are some procedures that cannot be rushed. For instance GPG is a time consuming operation.  Setting up for grinding requires meticulous precision. Grinding itself is a slow process and plating typically takes 14 to 25 hours for proper deposition.  Run-in is a process that cannot be rushed. So there are a number of factors that will determine the minimum time necessary to repair a spindle.

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4. What is QTA?

If you need your production critical spindle back right away ask for our QTA (Quick TurnAround) service.  Your spindle goes to the head of the line. All components not in stock are expedited next day or courier. Typical repair time for spindles not requiring GPG is from 1 to 2 days after approval of the quote.  If plating is required repair time is typically 3 to 5 days.

There is an additional charge for QTA service. QTA service is not always available.

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5. What is GPG?

Grinding the ID of a Hitachi Routing Spindle on our Kellenburger

Bearing journal dimensions are critical. For maximum life and spindle performance worn journals must be restored to manufacturer’s specifications.  If your spindle has worn journals, out of tolerance tool holder or other worn dimensional critical areas these may require “Grind-Plate-Grind”.

Worn areas are first ground to a uniform undersize dimension. This is the first “Grind”. The part is then hard plated to an oversize dimension. This is the “Plate”.  After plating, the part is re-ground to the exact nominal dimension; the final “Grind” of GPG.

HST works with tolerances to +/- 50 millionths of an inch (.00005”) to make sure your precision bearings have a precision fit. Once ground to size, rotating components are rebalanced to ISO 1940/1 G0.4.

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6. What is Kiss Grind?

Often a spindle requires a “kiss” or “breeze” grind. This is a light grinding that does not require subsequent plating and regrinding. Just enough material is removed to correct minor imperfections. This procedure is most often done on tapers and shaft faces to ensure perfect tool holder interface.

If the spindle taper does not exactly conform to the tool holder taper, the tool may be able to move slightly. This can cause poor part quality and bad tolerance. A perfect match is an absolute must for high quality machining. Verifying taper quality at HST is SOP.

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7. How much will it cost to repair my spindle?

That is one of the first questions we hear from new customers. To provide an accurate price quote we need to know the extent of the damage. There are many factors that affect the ultimate cost of a spindle repair. Is it only a failed bearing? Does it need GPG? Are multiple components damaged? What is the journal TIR? Are the journals within spec? Is the housing within spec? The dimensional tolerances for high precision spindles are measured in less than 1/10,000 of an inch. These and many other aspects of the spindle are examined before an accurate repair cost is known.  When HST quotes a repair, that is the number we stick with. We never “bait and switch”.

None the less, our customers often ask for an estimate before they ship the spindle. Any estimates provided prior to our examination of the spindle are provided in good faith to help our customers get a feeling for the range of cost that might be encountered. We want our customers to be aware that the cost of a comprehensive repair can be more than double that of a “basic” repair. All good faith estimates are subject to change.

No Risk

All of our quotes are no obligation and free of charge. So, the best bet is to send it to us for examination. Your spindle will be broken down, cleaned, examined and critical dimensions measured. If you decline to have the spindle repaired, we will return the cleaned parts or send them to a second repair house of your choice free of charge. All components will be photo documented. Note: it is often impossible to re-assemble catastrophically damaged components. In cases where the repair is declined and reassembly is impossible the spindle will be returned disassembled.

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8. What is Forensic Engineering / Quality Assurance (FEQA)?

HST developed the FEQA program to take Quality Assurance to another level of customer service.

Forensic Engineering is the investigation of components that fail or do not function as intended. Our purpose for forensic engineering is to locate the cause of failure with a view to improving the performance or life of the spindle.

Quality Assurance is defined by ISO 9000:2000 as “providing confidence that requirements will be met”. It is our systematic plan of action necessary to provide adequate confidence that your spindle will perform up to OEM specifications. Quality assurance includes quality control.

Combining these in our FEQA program we not only examine our in-house procedures for providing top quality repairs; we also look at the cause of failure with a view toward helping our customers improve their operations and increase spindle life. This can result in less down time and higher production for our customers.

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9. What is imbalance and how is it corrected?

Imbalance is caused by the displacement of the mass centerline from the rotational axis which is a function of eccentricity in the distribution of the rotor mass. It is measured in units of mass and distance, e.g., gram-millimeters or gmm.  Imbalance is considered in single plane modes and dual plane modes.

Balancing is the correction of this mass displacement by the removal, addition or adjustment of mass to the component to compensate for centerline error. Most high speed spindles are balanced by the appropriate removal of mass. Some larger machine tool spindles have pre-drilled and tapped holes for the addition of set screws which facilitates the addition of mass to compensate imbalance.

There are two general forms of balancing: "Static" and "Dynamic". Static balancing (which is not really static) involves installing the component into a balancing machine and measuring the "heavy" point in relation to the centerline, while the part is rotating. If the required balance correction is at a single axial point on the rotor the balance is said to be "Single-Plane". Single plane balancing is adequate for rotating bodies with a low length to diameter ratio (l/d).

Dynamic or "Dual-Plane" balancing is required for components or assemblies of significant length. Rotors with some axial length can have two "heavy" points at opposing ends of the component, acting independently on the mass center line. In order to balance the component, both planes must be corrected for center line error. Dynamic balancing is required for components such as shafts and multi-rotor assemblies.

HST operates several different balancing machines depending on the size of the rotating components.  Often we will receive spindles with over correction or balancing correction 180 degrees apart. It is necessary to qualify the shaft prior to balancing. Failure to do so can result in the incorrect balancing that is sometimes observed.

The Disco Spindle Shaft had gross over correction. HST recommends qualifying the shaft dimensionally prior to balancing.	Justin is balancing a Westwind shaft on one of our Schenk Balancers

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10. What is ISO 1940/1 G0.4.?

ISO 1940/1 is an international standard used for qualifying the balance of rotating rigid bodies. G0.4 is a particular balance grade within the overall standard. Compliance with this standard requires that the maximum residual imbalance falls within certain limits dependent on the overall mass of the rotating body. Grade G0.4 is on the finer end of the spectrum and typically the qualifying range for high speed precision spindles.

Some standard ISO grades and their applications are listed below:

• G16 Drive shafts, engine components, engine crankshafts
• G6.3 Marine main turbine gears, pump impellers, electric armatures
• G2.5 Gas and steam turbines, turbo compressors, computer memory drums
• G1 Grinding machine drives, small electric armatures, phonograph drives
• G0.4 Gyroscopes, Spindles, precision grinders

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11. How Does HST Qualify a Spindle Repair?

Testing the thrust capacity on a Disco Dicing Spindle

Before a technician signs off on our “Certificate of Quality” the spindle is subjected to a 28 point inspection *, one of the most comprehensive in the industry. This inspection looks at everything pertinent to proper spindle operation. Some of the items on the list include the following:

• Motor winding condition
• Journal dimensions
• Taper condition
• Assembled TIR
• Coolant flow
• Air consumption
• Thrust capacity
• Radial load capacity

Of utmost importance is the performance data. Some of the critical points are:

• Vibration Analysis
• Dynamic Run-Out

The technician and the QA inspector will not sign off on the report without reviewing every pertinent point.

* Some inspection points are not valid for certain spindles.

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12. What is HST’s warranty?

HST was the first independent spindle repair shop to offer a warranty equal to or better that the OEM’s. Every spindle repaired at HST receives our “Certificate of Quality” and is covered under the “best in the industry” warranty. We warranty all completely repaired industrial spindles against defects in parts and workmanship for a period of six months. All PC spindles warrantees are for 90 days.

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13. What conditions void warranty?

High Speed Technologies is very proud of our warranty and we stand four square behind it. The caliber of our technicians and the quality of our test procedures give us confidence to make this stand. However, our warranty does not cover failures due to mishandling, improper use, lack of or improper lubrication, or contamination.

Prior to shipping a spindle, HST runs-in each spindle and logs vibration analysis on one of our Vitec Analyzers. This information is part of the permanent record maintained in our data base. Each analyzer is certified. The calibration is traceable to NIST and compliant with MIL-STD 45662A.  After run-in, each spindle is run to speed and analyzed for balance, noise, dynamic run-out and heat build-up. When we ship, we are certain that the spindle meets or exceeds OEM specification.

In our FEQA program the spindle is dismantled and examined. Most often there are tell-tale indicators for the cause of failure. A few of the indicators in rolling element spindles include:

• Is there indicators of moisture in the housing
• Is porting clear of obstructions
• Is there contamination in the porting
• Is the shaft free of contamination indicators
• Are the bearings free of contamination indicators.
• Are there indication of crashes
• Are there indicators of overheating
• Are there indications of impact

If any of these indicators are present, the spindle is subjected to a second review. After the second review a determination is made concerning warranty. In every case the customer is provided photo documentation and an explanation of the cause of failure. We are always open for discussion and try to assist our customers in every way possible to avoid premature failures.

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14. What can I do to increase my spindle life?

Increased spindle life starts out with the proper repair.  Using parts that meet or exceed OEM quality. Proper handling and preparation for shipping is the next vital step for long spindle life. Packing must protect the spindle from impacts, vibration and moisture. The spindle should be unpacked using care not to jar or impact the shaft.

• When installing never strike the spindle.
• Use dry filtered air for float. As a minimum the following specifications should be applied to the compressed air:
• Dew Point –45 degrees C
• Local Filter 0.05µm absolute or finer.
• Verify spindle float  for a few seconds prior to start up.
• Initial operation should be at 10% maximum speed for a few minutes.
• Then the spindle should be ramped up slowly to normal operating speed.
• Verify tool condition and never exceed recommended feed rate.
• Verify tool holder condition, never use worn or damaged tool holders
• Never direct tool coolant at shaft seal and avoid excessive particle build up around shaft seal.
• Verify proper spindle cooling.
• Allow spindle to come to a complete stop prior to stopping float air.
• Never rotate spindle shaft when it is not floating.
• Use only HST to for repairs.

Once an air bearing spindle is up and running it should provide years of operation when correctly used. They only have one moving part and it is floating in air.

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15. Does HST Provide Field Service?

Although HST does not provide field service, we have established a number of strategic alliances with highly qualified service providers. These technicians are fully qualified to handle dicing saw repairs and back grinder repairs.  Call us, we can help.

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