Jena Tec MF option linear guides keep going and going...........

Expensive lubrication systems become a thing of the past and for machines without lubrication, Jena Tec's SBC MF series linear rail option extends the life and performance of your linear system by a significant factor.

The MF Lubricating Seal now offers longer life for SBC Linear Rail Systems, eliminating the necessity for periodical greasing. The MF Unit contains high quality ,grease filled fiber seals which will guarantee total surface lubrication and long maintenance free bearing life. The polymer housing containing the surface contact seals are tolerance matched to the guide rail to ensure perfect sealing and smooth motion.

MF Seal Units are grease filled and the lubricant is contained , spread and absorbed by the fiber seals. Using grease rather than oil ensures that the lubricant is retained within the MF seal units for a much longer working life than oil would remain. The grease used would be compatible with most standard industrial grades recommended for use in bearing blocks and provides excellent thermal stability and water proofing characteristics.

Tests conducted by SBC show a clear advantage of MF type seals, despite a modest increase in overall length through the slim line design of the fiber seal housing. Results show that for a standard theoretical distance life time calculation of a heavy pre-loaded guide block that the distance for an MF type under heavy load can be increased by 40% up to a 1000Km with no sign of degradation or wear affecting performance or accuracy. For light pre-loads the life extension can be up to a factor of 10 times. Even then replenishment with new MF end caps is a very simple straightforward procedure to give a further period of un-interrupted service.

For more information, contact the Jena Tec team on +44 (0)1623 726010 or email sales@jena-tec.co.uk or visit http://www.jena-tec.co.uk/

Intelligent GMN UHS Spindles from Jena Tec UK

In addition to our own manufactured range of high quality B&T customised spindles for milling, turning, boring and grinding, Jena Tec represents a high quality German brand GMN Nuernberg in the UK market for high speed and high frequency machining spindles.

In this issue, we've provided some detail information about GMN's capability in ultra high speed grinding spindles. Conventionally supplied by air bearng spindles which have some limitations and disadvantages in terms of cost and running efficiency, GMN's UHS series provides a robust oil lubricated grinding spindle for exceptionally high speeds up to 250,000RPM coupled with an exacting stability and geometric tolerance. A minimised oil/air dosing system means just the right amount of lubrication gets to the spindle and reduces maintenance and running costs throughout the life of the spindle.

Jena Tec's automation division can offer the UHS series from GMN including integration or retrofit to existing machines. If you would like to discuss how we can offer you the advantage of higher speed and better process performance from your grinding machine, then give our UK office a call on +44 (0)1623 726010 or by email to sales@jena-tec.co.uk

Intelligent Spindles from GMN**

Processing small internal diameters with optimum cutting speeds requires high rotational speeds. New GMN spindle ball bearings with very high speed characteristics permit 250,000 revolutions per minute, for instance, with comparatively high spindle rigidity and load capacity. Optimized lubrication of high speed spindles offers great potential for increasing performance. Furthermore on-demand minimal lubrication lowers oil consumption and increases service life. In future integrated data loggers will monitor the condition of the spindle, store the operating parameters and guarantee high availability. GMN has a long track record of supplying a wide range of high frequency spindles of up to 180,000 rpm. However, around two-thirds of the spindles supplied for internal grinding operate with maximum speeds in the 30,000 to 90,000 RPM range.

250,000 RPM for small bores
To operate efficiently, a machine tool spindle must have the appropriate load capacity, rigidity and dynamic run out. In order to guarantee these characterisitcs even for extremely high speeds, the GMN development department was faced extraordinary challenges. Breaking points are reached due to the high centrifugal forces, a compact design has to ensure subcritical operation with sufficient distance to the first critical speed, high precision hybrid ceramic bearings have to be designed specifically for the demands of high speed spindles. These challenges were met wth the the help of current advances in motor technology and the use of further developed GMN spindle ball bearings. It is now possible to efficiently grind small internal geometries with up to 250,000RPM. The GMN grinding spindles used for this purpose have a comparatively large and rigid mounting and a powerful sychronous motor. Consequently, they are not only suitable for special applications at maximum speeds but can also be used flexibly and efficiently in a relatively large rotational speed range.

Integrated lubrication module
These days, ball bearings with permanent grease lubrication or oil/air lubrication are predominantly used in machine tool spindles. Yet both methods have their disadvantages which can be overcome by an innovative micro-dosing system combined with appropriate lubrication strategies. Compared with today's oil/air lubrication method, a significant reduction of the lubricant quantity necessary can be achieved and the systematic performance limits of grease lubrication. I.E. Limited usable life of grease at high temperatures and speed, are to be exceeded. Minimizing lubricant quantities makes ecological and economic sense. It facilitates the inegration of an oil reservoir in to the spindles and ideally requires no more external components. The problems associated with waste oil disposal are also defused. Operating costs of machine tools can exceed acquisition costs several times over if calculated over a normal life cycle. These costs are therefore a decisive factor for many users when making an investment decision. An integrated lubricant cartridge means that high maintenance external components can be dispensed with. The lubricant reservoir only needs to be replaced at relatively long intervals. An almost instant dosage of lubricant ensures that the adjustment of the lubricant quantity matches demand based on the exact measurements of the bearing. This increases reliability and efficiency of the bearing and reduces the quantity of the lubricant needed.

Third generation spindles for machine tools
Spindles are also becoming more and more intelligent. Miniaturised electronics which are integrated in the spindle stores the sensor signals, processes them and reports any exceeding of critical values to the overall machine control system. Important operating data can be accessed during the entire running time of the spindle and can also be analyszed with regard to optimising the process, machine and spindle. In addition, the aim is to go for bearing condition monitoring and consequently early damage detection,based on these intelligent systems is possible. Evaluating temperature sensors, position sensors and vibration sensors will increase precision and productivity of the production process. Additional sensors, on the other hand, harbor the risk of reducing the availability of the spindle system further, therefore, as few additional sensors as possible should be employed and for the time being, a more intelligent analysis of available signals should be aimed for.

** Reproduced from an article by Dr. Bernd Moeller, Head of Engineering Spindle Technology Division at GMN Paul Mueller Industrie GmbH & Co. KG in Nuernberg, Germany.

For service and support on design, selection, repair and replacement of spindles from GMN in the UK from Jena Tec go to www.jena-tec.co.uk or call our UK office on +44 (0)1623 726010

Principles of Ballscrew Repair

Principles of Ballscrew Repair

What exactly does happen to a ballscrew when it fails and what are the principles and procedures to repair a ballscrew from a company such as Jena Tec?

The most frequent cause of failure of a ballscrew is either loss of pre-load or rough running typically characterised by a fault flagged by a CNC control system of a machine tool or dimensional inaccuracy or poor surface finish. This in turn is caused by gradual degradation of the ballscrew surface through metal to metal contact of the re-circulating balls to the hardended metal surface of the ballscrew shaft. This repeated contact over an extended period of time leads to a worsening of the ballscrew surface and ultimately erosion and wear.

Lubrication can therefore have an obvious impact on the lifetime of the ballscrew as well as protection from debris from the machining processes. Over time as a machine condition worsens, axis covers and bellows can be damaged and allow machining debris to enter the ballscrew nut even through wiper seals. Over lubrication can also be problematic particularly with grease lubricated systems where too much lubrication can cause pressure on the ballnut return system causing the tube to literally burst with excess grease.

The second most frequent cause of ballscrew failure is catastrophic failure due to an exceptional shock load, which is more commonly recognised as a machine crash. The abrupt excessive load and rapid decceleration from a machine crash can cause buckling of the ballscrew shaft and damage to the ballnut itself including splitting some of the re-circulating balls within the ballnut meaning even if the machine runs afterwards the ballscrew will very quickly fail after a short period of running.



Typical Ballscrew Failure Points

A - Metal Fatigue & Wear to Bearing Surfaces
B - Surface Brinelling
C - Wear & Damage to Balltrack
D - Loss of Squareness to PCD
E - Ball Wear/Breakage
F - Loss of Pre-Load
G - Shaft Bent
H - Damaged Threads
I - Uneven wear over Balltrack
J - Poor System Concentricity
K - Wiper Seals Worn Leaking Lubricant
L - Excessive Backlash
M - Return Mechanism Worn/Broken

The good news is that for routine wear, a ballscrew life can be extended for a further period of service by a very straightforward procedure of repair of the ballscrew by a company such as Jena Tec. Firstly, the ballscrew is checked for its initial condition, this includes checking its free running condition and the "as received" pre-load or drag torque. The ballscrew then undergoes a 32 point healthcheck to check the major points contributing to the ballscrew performance. You can see some of the major areas of inspection referred to above.

After extensive cleaning and checking, the ballscrew, if repairable, is polished along the length of the ballscrew track and undergoes ultrasonic cleaning of the ballnut coupled with high pressure washing to remove baked on grease and grime. The ballscrew assembly is then re-built with oversized micron graded precision ball bearings to achieve a satisfactory level of pre-load along the length of the ballscrew according to DIN specifications.

The unit is then put on extended test and Jena Tec facilities include the ability to document and test the ballscrew running performance on motorised testing rigs. Where a ballscrew passes, a complete documented test report is provided for the customer detailing the received condition and the pass criteria with drag torque graphs and certificates of conformance. Based on Jena Tec's expert assessment, the unit is warrantied with recommendations for the customer on the extended life period.

While many claim to offer ballscrew track re-grinding, Jena Tec advise that due to a weakening of the induction hardened surface and also the cost to re-grind, that in most cases it does not make economic sense to re-grind the ballscrew track form. It is however feasible to re-furbish bearing end journals by hard chrome plating or metal spraying and then re-grinding with a precision universal grinder to exacting bearing fit tolerances. Fixing thread forms are always checked, cleaned and re-furbished where possible as well as wiper seals, fixing key ways and a variety of related small details.

What happens when the ballscrew is not in a repairable condition? Not all is lost, as most ballscrews can be repaired to give a shorter extended life, but in this instance Jena Tec would not offer a warranty but strongly recommend the customer buys a new replacement unit. Jena Tec's extensive stock of precision ground, rolled and whirled product means that we can offer a matched replacement sometimes within the same working day to provide an OEM quality replacement ballscrew.

This means that Jena Tec has the ability to support not only your repair requirements but also your spare parts backed up by our highly trained linear motion technicians, high stock levels and capable precision machine shop.

Typical makes and types of ballscrew repaired by Jena Tec include;

THK NSK Steinmeyer Mannesmann
Hiwin PMI ABBA Comtop
20th Century TCM Blis Berger Bosch
SKF PSI Saginaw Nook
Rockford Nachi Thompson IBL Star
Shuton Iperanga Korta LSI
Barnes American Ballscrew Warner Electric


For service and support on design, selection, repair and replacement of ballscrews and linear motion from Jena Tec go to www.jena-tec.co.uk or call our UK office on +44 (0)1623 726010

Jena Tec 50% Ballscrew Repair Discount

We all know the current economic situation, times are tough and maintenance budgets slashed but some machines just have to keep going and need to be repaired. Let us ease the current economic chill just a little and make you aware of our fantastic winter offer for ballscrew repairs.
Send us your failed ballscrew for repair assessment and we will give you a 50% discount off the repair price. All prices are quoted on a standard length and diameter matrix meaning you get a great genuine discount coupled with the outstanding service from Jena Tec.
But don't delay, this offer lasts until January 2010, ring our UK sales office on +44 (0)1623 726010 and ask for your free discount voucher code**.
Then next time you have a ballscrew failure, ship it in, we'll check it over and provide our detailed repair report and commercial offer. If you decide to go ahead place your purchase order and quote your voucher reference, it's that simple, a great discount of 50% on your next repair.
Contact Jena Tec on +44 (0)1623 726010 or email to sales@jena-tec.co.uk
Jena Tec repairs ballscrews of any make, type or configuration with whichever type of ballscrew transfer system. Our specialized repair and ballscrew testing facilities mean we can repair ballscrews up to 15m in length and 200mm in diameter. Because Jena Tec design and manufacture ballscrews, we like to think we know a thing or two about ballscrew repair to give the you the customer a first class 1A ballscrew repair. We can offer express ballscrew repair out of hours and while you wait. We can collect your failed ballscrew needing repair or be available to accept your delivery 24/7. Upon receipt of your ballscrew, we log your ballscrew onto our repair system and provide our free of charge assessment report. Measuring critical parameters and conducting a 32 point ballscrew repair check means we offer an unrivalled service for ballscrew repair internationally. Additionally, Jena Tec’s ballscrew repair service technicians can assist with removal and refitting of your ballscrew at your request. Backed up by extensive OEM precision ground, rolled and whirled ballscrew stock designed specifically for the ballscrew repair market, Jena Tec offer rapid reverse engineering and emergency replacement of your failed ballscrew should repair not be possible. Not only that but Jena Tec’s ballscrew upgrade service means that often we can diagnose the failure mode of your ballscrew and offer a drop in replacement with our XLF series precision ballscrews.
Jena Tec offers International, European, UK and USA ballscrews repairs so just give our hotline a call to make arrangements now. It’s as simple as A B C for linear motion and ball screw repair services from Jena Tec. Keep an eye out for our special offers relating to Jena Tec ballscrew repair.
Not only can Jena Tec repair ballscrews, we can also repair your ballscrew and belt driven linear actuators, gearboxes and lifting jacks. Jena Tec’s repair capabilities include hard chrome, re-grinding, reverse engineering and replacement engineering of spare parts within the ballscrew, actuator or gearbox range.
Ballscrews and Actuators Makes & Manufacturers we can repair include;

THK
NSK
Steinmeyer
Mannesmann
Hiwin
PMI
ABBA
Comtop
20th Century TCM
Blis
Berger
Bosch Rexroth
SKF
PSI
Saginaw
Nook
Rockford
Nachi
Thompson IBL
Star
Shuton
Iperanga
Korta
LSI
Barnes
American Ballscrew
Warner Electric

**Terms and conditions apply. Excludes shipping and transportation costs to/from Jena Tec UK. Voucher is valid until 31st January 2010 against new valid purchase orders placed in this period for a single ballscrew repair. Discount is subject to credit and account status. This value is not transferable or available as a cash/credit refund.

Jena Tec joins European Power Transmission Distributors Association (EPTDA)

Jena Tec, a leading supplier and manufacturer of ballscrews, linear rail, actuators and machine tool spindles has raised its profile with the membership of the European Power Transmission Distributors Association http://www.eptda.org/ . EPTDA is one of the leading distributor trade associations in Europe and provides highly professional membership based services for distributors and manufacturers in the power transmission field. Jena Tec will commence with exhibiting at the EPTDA annual conference in September 2009. EPTDA is an ideal fit for Jena Tec as a manufacturer member is one of a limited number of manufacturers offering a complete range of linear and rotary motion components and assemblies through distibutor channels worldwide. For further information go to http://www.jena-tec.co.uk/ or www.eptda.org . Jena Tec company details are listed on EPTDA also. Alternatively contact Jena Tec on +44 (0)1623 726010 or by email at sales@jena-tec.co.uk

Jena Tec joins Bearing Net Supplier Network

Jena Tec a leading supplier of precision machine tool components including ballscrews, linear rail, actuators and machine tool spindles has joined the Bearing Net network to offer its customers a complete service including precision spindle bearings. By keeping extensive stocks for popular sizes in precision grades Jena Tec can offer a wide range of bearings grease packed, oil/air lubricated and hybrid ceramic from GMN, NSK, FAG, INA, SKF, SNFA for the OEM, distributor and MRO markets. For more information go to http://www.jena-tec.co.uk/ or http://www.bearingnet.net/

For further information, visit our website or alternatively call our UK office on +44 (0)1623 726010 or email at sales@jena-tec.co.uk

Jena Tec WBSVH Grinding Attachment for Vertical Lathes & Turning Machines

Adaption of a vertical turret lathe or turning centre into having a grinding capability couldn't be easier with the use of a Jena Tec WBSVH grinding head. Jena Tec design and manufacture the B&T WBSVH range to be customised to provide a range of extension lengths with 1.5 or 3HP versions at speeds of up to 6000RPM. The WBSVH motorised grinding spindle range is ideally suited to retrofit or periodic use as a grinding attachment for vertical lathes. The unit can be easily fitted by directly mounting onto a tool post turret position or by a suitable adaptor plate to allow the operator to remove when not required. Jena Tec also provide its range of CT portable inverters to allow speed control and constant torque through a suitable drive system supplied with cubicle and customer specified length of armoured cabling. The robust Jena Tec WBSVH spindle has a rugged cast iron body and durable AC motor. The extension sleeve is made from excellent quality steel and the entire unit is finished in a 2 pack epoxy paint coat to a high standard. Irrespective of extension sleeve length, the wheel location taper is ground accurately to within a few microns runout providing customers with the assurance of a high quality accurate grinding process. The Jena Tec WBSVH range is particularly suitable for grinding of honeycomb in aerospace, grinding of abradeable coatings, ceramics, hard facing, stellite coating and can be adapted to a wide range of vertical machining centres including Webster & Bennett. for further information go to http://www.jena-tec.co.uk/ or contact Jena Tec on +44(0)1623 726010 or by email at sales@jena-tec.co.uk .

Jena Tec Launches Precision Rotary Tables

Jena Tec announces two further models to its linear and rotary motion ranges in the field of precision rotary tables. The first model, the MRT230 is a lightweight ring grinding unit driven by a pancake segmented motor via a gearbox and toothed belt. The cast alloy base plate allows bolting directly to a grinding machine table.

Mounted on the rotary axes employing ABEC 7 angular contact bearings is a magnetic chuck, 230mm diameter providing load capability of up to 30kg. The central 40mm location spigot allows location of fixturing and the unit can be supplied with a variety of 3 jaw chucks and t-slotted face plates on request. The unit is supplied complete with an electrical control box providing infinitely variable speed control up to 120RPM. The MRT230 is an ideal solution for rotary grinding of bearing spacers and other applications where constant surface finish is important combined with accurate parallelism.

The second series is the ABRT Series Air Bearing Rotary Table. This expansive range provides a highly accurate rotational motion in either manual or CNC mode with minimal effort through the provision of an air bearing cushion. The unique hydraulic clamping mechanism allows rigid clamping for heavy duty machining. With table diameters from 500mm to 2000mm and table loading up to 10,000kg with repeatability of +/-0.2 arcsecs, the range is an exceptional high quality attachment suitable for a variety of applications in boring, milling, grinding and inspection.

The ABRT series can be provided with a torque motor option, encoder feedback and digital readout and can be fully integrated within a CNC control. Jena also offer an industrialised PC based CNC control allowing retrofitting to existing manual machine tools. Customised designs of ABRT rotary axes can be provided on request relating to higher loading, diameter, acceleration and tolerances.

For further information, go to http://www.jena-tec.co.uk/ or alternatively contact our sales office on +44(0)1623 726010 or by email sales@jena-tec.co.uk

Jena Tec secures long term contract in China

Jena Tec, a UK based designer and manufacturer of precision machine tool ballscrews, linear motion and spindles with facilities in England, USA and Germany, has secured a long term contract with a customer in China for the supply of a high precision spindle used in an accurate CNC turning machine. The Asian customer will be producing highly accurate machine tools principally for export to Europe and North America and will utilise Jena Tec’s high performance spindle to satisfy the demanding requirements of small precision turned components.
Manufactured using carefully selected materials including nitride hardened rotating parts and precision grade rolling element bearings, the spindle is guaranteed to provide a concentric run out within 0,001mm (1 micron) with excellent thermal stability and low noise running at up to 6,000RPM. The spindle product is accurately ground using the latest precision equipment and assembled by hand by skilled machine tool personnel to attain the highest levels of accuracy. Each spindle is closely inspected and certificated as meeting the required standard which is documented to the customer.

Jena Tec, part of the Avingtrans plc Engineering Technology Group, was selected on the basis that it could design and manufacture a high precision product rapidly for prototype testing followed by volume production ensuring the customers’ product development programme was supported adequately.
The contract in total represents £1.8m for Jena Tec and was won against strong competition from Japan and Korea and further supports Jena Tec’s continued success in the niche sector of high precision linear and rotary motion components.
The name of Jena Tec is closely linked to the town of Jena in Germany where it has maintained one of its manufacturing facilities for over 30 years. The name of Jena is closely associated with Carl Zeiss and high precision scientific, medical and engineering industries with companies such as Carl Zeiss Jena, Jenoptik and Schott Jenaer resident in this famous University town.
Jena Tec is justifiably proud of its heritage and ability to adapt to the changing global economy by continuing to design and develop high precision products.
For further information on Jena Tec, go to http://www.jena-tec.co.uk/ or for Avingtrans plc, go to http://www.avingtrans.plc.uk/