Advanced Grinding Solutions

Krebs & Riedel who were founded in 1895 have been manufacturing high quality standard, diamond and CBN abrasives for over 100 years, and who were a founding member of the organization for safety in abrasives, are able to count leading UK engineering companies such as Perkins Engines, Grundfos and Delphi Diesel Systems amongst their ever-growing UK customer base. Krebs who employs over 250 people and continues to expand is constantly introducing new types of wheels with improved grain structures and novel bonding systems that enhance grinding wheel quality and optimise performance.

Sales of Krebs & Riesel wheels has increased with over 25,000 different wheel types, worth over £27m a year being sold with over 43% of sales being exported outside of Germany via a network of over 30 agents with the UK sole distributors being Advanced Grinding Solutions of Coventry.

One area where Krebs & Riedel excels in is the supply of very special wheels for gear and thread grinding applications and these special wheels are available to suit machines manufactured by Gleason-Pfauter, Oerlikon, Kapp-Niles, Hofler, Maag, Samputensili and Reishauer etc. Krebs are also a member of the WZL-Getriebekreis “Gear Research Circle” at Aachen University and are heavily involved in developing advanced wheels for the latest production technologies employed by leaders in the field of gear manufacture. So successful have the Krebs & Riedel gear grinding wheels been they have become the major supplier to leading machine companies such as Kapp.

In the automotive industry, for example, the demand for more efficient and quieter gear transmissions is pushing the gear grinding process to its limits. With the increasing number of vehicles having automatic and semi-automatic transmissions and with increased number of speeds (was once only 4 forward gears and now 8 or more is common), gears in average are getting smaller whilst production volumes are rapidly increasing.

Advanced Grinding Solutions (AGS) supplies Krebs wheels to several top UK gear manufacturing companies who are able to call off specially profiled wheels for gear production on fast deliveries. Under agreement Krebs can keep customers blank wheels in stock and upon order will profile these to suit and then supply within just 2 or 3 days.

Working closely together with key gear manufacturing companies, has now led Krebs & Riedel to develop a new type of gear grinding wheel called "Blue Moon". This wheel is ideal for continuous gear generation grinding, bevel grinding and profile grinding and is just part of a range of wheels offered by Krebs & Riedel for gear grinding applications, thread grinding and worm grinding where the aim is often to grind and achieve a polished finish in one operation.

Today many grinding machines use worm grinding wheels for gear grinding because they have advantages over form wheels; usually a faster cycle time. Given the growing popularity of gear grinding using the continuous generation that is complementary to the form grinding method, and does not replace it, then both types have a part to play in gear manufacture. The Krebs & Riedel Blue Moon wheels are ideal for both processes.

Single profiled wheels may also be specified for internal and external gear grinding applications as can MAAG dish wheels and profiled wheels for discontinuous generative grinding machines.

This brand-new and improved design of grinding wheel offers increased cost-effectiveness through extended dressing cycles and increased stock removal rates. The Blue Moon wheels have been specially developed for working speeds of up to 100 m/s (with fine grain sizes) although general working speeds of 40-63 m/sec are used for gear grinding with 70-80 m/sec on the newer grinding machines. Dressing intervals are lengthened through the use of specially selected grinding media mixtures of high-grade aluminium oxide, micro-crystalline sintered aluminium oxide and special aluminium oxide. The latest V85 Multo vitrified bonding system is employed for the Blue Moon wheels. Thanks to the optimum bonding of the abrasive particles, this special low temperature bonding system with its increased porosity is suitable for grinding speeds throughout the entire range.

Blue Moon´s newly designed grain combination optimizes the pore space and the special grain geometry improves cutting ability; this increases overall cutting performance and reduces cycle times for maximum efficiency. Blue Moon wheels are made to the highest quality and can be supplied unprofiled or pre-profiled for gear modules 1-12 as required by customers. The wheels are perfect for gear grinding machines manufactured by Gleason, Kapp, Liebherr, Reishauer, and Samputensili etc.

The key focus on development of the Blue Moon wheels was to ensure that the wheels would cut harder, and faster, and for longer periods of time, before dressing is needed. The last remaining important performance target for this wheel was to reduce the risk of damaging the gears due to so called grinding burn which is a major cause of overheating gears and is directly related to premature grinding wheel wear before a planned dressing routine.

During the grinding process, the abrasive particles of the grinding wheel can become blunt due to wheel wear; this blunting of the wheel also quickly reduces its cutting ability and lengthens cycle times. Once worn in this manner the abrasive particles can become loosened from the bonding material and break off from the wheel itself which turns the wheels surface shiny and smooth. The then smoother wheel generates and then transfers more heat to the gear due to a then higher friction rate which causes wheel burn and will subsequently rapidly degenerate the wheels leading to a complete failure.

To overcome this problem gear grinding wheels need defined dressing frequencies to sharpen the wheels and to expose new abrasives grains on the surface of the grinding wheel. However, wheel dressing itself wears wheels down and is therefore expensive so lengthening the frequencies between dressing is another very important factor of the Blue Moon wheels.

It is important to note that Krebs & Riedel also offers a range of Diamond and CBN Superabrasive wheels, that have been manufactured by them for more than 25 years, and are also available from 3mm to over 900mm in diameter with peripheral grinding speeds of up to 200 m/s. The major grinding disciplines that Krebs offer wheels for include cylindrical grinding, surface grinding, creep feed grinding, special profile grinding, gear grinding, centerless grinding, and the non-round grinding of cam forms etc. Recently the use of dressable vitrified CBN grinding wheels for gear grinding applications has increased and Krebs also offers solutions for this application.

Such has been the success that Advanced Grinding Solutions had in the UK with the Krebs & Riedel wheels they now hold over £75,000 worth of wheels in stock for the same day/next day delivery to key UK customers and this stock holding is growing as more and more engineering companies discover the advantages in improved part quality and in cost savings that the Krebs wheels brings to them.

Furthermore, unlike some other grinding wheel companies, AGS understands that many end users do not want to purchase lots of wheels for stock if that can be avoided and therefore for most grinding applications there is no real minimum order quantity.

Some of Advanced Grinding's UK customers literally only order a single wheel two or three times a year, whilst others have several hundred wheels every month. Some buy huge CBN wheels that can be expensive and others need small internal grinding wheels costing of course a fraction of that. Krebs is really able to support all customers – both large and small.

Customers wishing to improve their grinding processes are invited to contact AGS who can arrange for free of charge test wheels to be made available to prove out the superior quality and efficiency that is achieved when choosing the latest wheel technology from Krebs & Riedel.

Anyone wanting to arrange a no-obligation grinding trial using Krebs wheels should contact Advanced Grinding Solutions Ltd on +44 (0) 2476 22 66 11 or via their website www.advancedgrindingsolutions.co.uk accordingly.