Considering the steady growth in the demand for gears in industries such as automotive, power transmission and aerospace, it is no wonder that gear manufacturers are looking for solutions to decrease their gear grinding cycle times while reducing noise emission from the gears.

CUMI constantly works on solving such issues and offers comprehensive solutions for gear grinding needs.

Dr. Xavier Kennedy, General Manager – Head of R&D, CUMI

Abrasives are materials used to grind, abrade or clean work pieces to achieve the desired shape and finish. Abrasive technology is challenged by work piece materials, stringent surface quality requirements, manufacturing process changes and aggressive cost targets. Gear grinding is one of the critical processes in forming transmission components. This involves a relatively high contact area between the tool and work piece and is extremely sensitive to mechanical and metallurgical damages.

Challenges in gear grinding processes

As far as materials and design aspects are concerned, requirements of aerospace industry, automobile industry, and energy sector have pushed the envelope in developing special materials and tolerance limits by design.  Advancements in grinding machines with multitasking features has resulted in many advantages such as reduce set-ups, reduced tooling and fixturing and increased work piece accuracy and most importantly even throughput. The increasing demand for high efficiency and noise emission of gears pushes the gear grinding process to its limits. With the widening range of applications for automatic planetary transmissions and increased number of speeds, gears in average get smaller and smaller, while production volumes are increasing. The same applies to industrial applications. The movement towards the smaller gears result in shorter grinding times.  Over the past decade, productivity and profile accuracy, no burn and fatigue strength in hard gear finishing are the challenges that a grinding wheel manufacturer faces.

Due to current economic conditions as a solution provider, tool suppliers in the industrial market place are consistently challenged by our customer need to reduce costs. This calls for immediate action to check costs and provide customers with a suitable solution that addresses Total Cost of Ownership.

TCO – Gear grinding wheels

CUMI’s constant innovation and product up gradation, through in-house R&D and strategic alliances with global leaders in grinding technology, have ensured international recognition as a manufacturer of quality abrasives and a provider of total grinding solutions. At CUMI’s state of art facility of making gear grinding wheel with new micro crystalline abrasives, advanced new profile making system, breakthrough engineered ceramic bonding designs and revolutionary manufacturing technologies, all come together under one roof for the development and production of the next generation of bevel and cylindrical gear grinding tools. CUMI has been providing gear grinding solutions which includes Single rib and Multi rib gear grinding wheels.

CUMI Grinding Wheels for Gear Grinding

Single Rib Gear Grinding Wheel
Grain
Tier Grit Type Features Benefits
Good RA Controlled Fracture Cool Cutting
Better 1CUMISA Micro Crystalline Grain Self-Sharpening
Lower Dressing Depth
Bond
Tier Bond type Features Benefits
Good V736  

Higher strength Bond Post

Lower cycle time
Lower Dressing time and depth
Best VCA2 Progressive fracture Form Holding
Longer Life
Multi Rib Gear Grinding Wheel
Grain
Tier Grit Type Features Benefits
Good SA Controlled Fracture Free Cutting
Better 3CUMISA Micro Crystalline Grain Better Profile  Accuracy
Better Lead Accuracy
Bond
Tier Bond type Features Benefits
Good V677 Higher Bond Post Lower Dressing Depth
higher Strength Burn Free Components
Best V736 High Speed Bond Form Holding
Longer Life

Gear grinding solutions – wheels for high stock removal and combination grinding and finishing

Grind and Finish

Super finishing the working surfaces of gears and their root fillet regions results in performance benefits. A super finished surface of gear tend give free of stress raisers, damaged metal and peak asperities, all of which reduce the life of the gears. These gears will experience reduced friction, lower operating temperature, less wear, better scuffing resistance, and better contact fatigue resistance.  The process of continuous grind and finish been accepted practice in gear industry. CUMI has developed a wheel for grinding and finishing of gears. The finishing portion of wheel is made with high resilience polymer bonded fine abrasive. The resilience of the finishing wheel can be altered to suit the work piece and grinding parameters (Figure 1).

Higher productivity with predictable performance

Productivity and migration of machining to grinding demands the higher material removal in the grinding process and in turn reflect higher Q’.  CUMI’s engineered abrasives with specific geometry coupled with functional bonds helps in achieving Q’ of 24 against normal value of 16. These engineered grains are not only tough but have a low bulk density. The uniqueness of shape and distribution gives more interconnected porosity and good accessibility of coolants to grinding zone.  High level of porosity ensure uniform stock removal. These next generation wheels increase the throughput, significant reduction in wheel dressing frequency, minimizes the possibility of grinding burn and offer reliable and consistent grinding performance (Figure 2).

Single Rib Gear Grinding Wheel
Grain
Tier Grit Type Features Benefits
Best 3EX Engineered Grain Faster Cutting
High Coolant flow Burn Free & Methodological Damage
High Porosity Higher Q’
Bond
Tier Bond type Features Benefits
Good V736 Higher strength Bond Post Lower cycle time
Lower Dressing time and depth
Best VCA2 Progressive fracture Form Holding
Longer Life

Figura 2:

Mola abrasiva con granuli modulari

Multi Rib Gear Grinding Wheel
Grain
Tier Grit Type Features Benefits
Best CUMISA /Fines Coarse/ Fine Grain Burn Free
Roughing / Finishing in Same operation
Capable to take higher feed rates
Bond
Tier Bond type Features Benefits
Good V677 Higher Bond Post Lower Dressing Depth
Higher Strength Burn Free Components
Best V736 High Speed Bond Form Holding
Longer Life

Figure 1: Super finishing tool.

Fine abrasive grain with resilient bond

dr-xavier-kennedy

Author: Dr. Xavier Kennedy

Carborundum Universal Limited (CUMI), India, is a part of the US$ 4.6 billion conglomerate Murugappa Group. It is a fully integrated surface engineering company with capabilities ranging from manufacture of high performance abrasive grains, bonds, application engineering and design of abrasive wheels for diverse and demanding applications across industries.

www.cumiabrasives.com