Grinding as a geometrically undetermined machining process is widely employed, whether processing moulds or removing sprues in foundries, in machinery, tool or jig construction, in industrial steel construction or the automobile industry. Abrasives are used to process the surfaces of widely varied materials such as metal, wood or plastics or used to separate materials. Every grinding process is based on two components, whether manual or used in stationary applications, the grinder and the abrasive, and they must be carefully matched to obtain an optimal end result.
Dr. Michal Hubálek, Head of Development at DEPRAG CZ a.s. and responsible for the pneumatic tool product area DEPRAG INDUSTRIAL gives us the inside story and reveals that it is this balance in particular which is indispensable for efficient and ergonomic processing within industry. When this balance is right, it can mean enormous savings in time and costs for many applications.
“Our customer, a well-known manufacturer of cast iron pump housings, came to us requesting that we re-examine their working procedures and find out where they can optimise” recalled Dr. Hubálek. “First of all we analysed the current situation on site. It is important at this point to not only inspect the grinder but also the abrasive used in the customer’s application” explained Dr. Hubálek. His customer could reach a max. grinding speed of 32 m/s. Upon closer inspection of the technical details it was discovered that an abrasive was being used which allowed for a maximum speed of 15,000 rpm. For the processing of cast iron parts the customer opted for the straight design grinder with vane motor GDS100-190BX from the comprehensive standard catalogue of DEPRAG INDUSTRIAL tools. This grinder with its power output of 1 kW and an idle speed of 19,000 rpm is the optimal solution for that abrasive previously in use.
After examination of the current situation the DEPRAG technicians become active. “Our goal is to increase productivity. This is basically attained by increasing the grinding speed. For optimal processing of the cast iron parts we selected the straight design grinder type GDST100-280 BX with power output 1 kW and idle speed 28,000 rpm for the customer”. In order to enable this turbine grinder to be effective a suitable abrasive which allows higher speeds is also required. And this abrasive was found straightaway by the application technicians at DEPRAG. The recommended abrasive allows speeds of 29,800 rpm, almost double the speed of the abrasive previously in use. “However our customer was not well pleased when he first heard the purchase price of this high quality abrasive. It seemed to him at 2.90 Euro per piece much too high in comparison with the previously used cheaper abrasive at 0.70 Euro a piece” recalled Dr. Hubálek of the initial customer reaction to the suggested new solution.
“But it is not as simple as that. Whether a solution is economically viable is proven in field tests. This field test was carried out with the turbine grinder and alternative abrasive on site” said Dr. Hubálek. A grinding speed of 47 m/s was achieved using the innovative turbine grinder. This is around a 46% higher speed than previously achieved in this application. And that is not all, “this field test proved that the change to a turbine grinder not only saves processing time but also that the new abrasive lasts 4 times longer. The customer had not initially taken this increased lifespan of the abrasive into consideration” explains Hubálek.
Dr. Michal Hubálek relates the facts in comparison to the customer’s running operations. They work in shifts and process 1500 cast iron parts per week. “1 shift session was not sufficient without overtime under the previous grinding solution. But due to the faster processing of the turbine grinder type GDST100-280BX and corresponding abrasive so much time is saved that overtime is no longer necessary. Together with the 4 times higher lifespan of the abrasive, the total cost comparison is a saving of over 30%!”
The customer wanted to know what other advantages could be gained as well as the cost saving. Dr. Hubálek explains “There is also the oil-free and almost maintenance free operation. Grinders with vane motors must have their vanes changed regularly but this is no longer necessary with turbine drives”. The turbine grinder scores highly on its wear-free magnetic brakes with which the run time of the grinding tool is considerably decreased by over 30%. Furthermore an integrated speed regulator reduces the air consumption dependent on load. Additional plus points of the 1 kW output GDST100-280 BX are the light weight body and low sound level of only 75 db(A). The robust design of the DEPRAG INDUSTRIAL grinders ensures a high lifespan of the tool in continuous industrial use.
“Application cases such as with the cast iron housing, are not unusual”, according to Dr. Hubálek. “We often deal with similar starting situations even though it is easy to save costs by making the right choice of grinder and abrasive”.
The components of the grinding process, the correct grinder and abrasive cannot be considered separately. The turbine grinder type GDST100-280BX with collet and the corresponding abrasive enable DEPRAG to provide the customer with an all round solution to optimise working procedures. The application specialists at DEPRAG have developed a customised solution which will produce the highest possible economic advantages. Dr. Hubálek continues, “with our wide range of grinders we can draw on unlimited resources to offer the most economic solution for every customer”.
DEPRAG's comprehensive program includes grinders with collets in power ranges from 90 W to 1,200 W at idle speeds of 11,000 to 100,000 1/min. These grinders are available in straight or angle design. Furthermore there are radial grinders with power ranges of 500 W to 2,400 W at speeds of 4,000 to 17,100 1/min. There are also angle grinders in power ranges 500 W to 4,500 W for grinding disc diameters of 100 mm to 230 mm available from the manufacturer. Angle grinders are available with direct drive or angular gears. Belt grinders are on offer at 300 W and speed 30,000 1/min and 500 W at speed 16,000 1/min. For stationary use the company has a wide variety of air motors available.
DEPRAG offers optimal and efficient customised solutions in over 50 countries of the world. DEPRAG SCHULZ GMBH u. CO. KG has its headquarters in Amberg, Germany and is represented with over 600 employees in more than 50 countries. As well as the range of pneumatic tools the core competencies of the company include screwdriving technology, automation and air motors.
DEPRAG SCHULZ GMBH & CO. KG
Tel: 09621 371-343
Fax: 09621 371-199