Grinding Operation - Industrial Engineering - Improvement for Productivity

Operation Analysis

Operation Analysis is an industrial engineering task that evaluates the engineering of each engineering element and other elements of other resources used in the operation and redesigns the elements when the productivity analysis points out or identifies an improvement opportunity.  Improving engineering elements is the core of industrial engineering activity. Improving human elements is the next important task. More areas were studied and are being improved by industrial engineers. But the core of industrial engineering has to be improvement of engineering elements and variables related to engineering elements to maintain the relevance of the discipline and competitive advantage of the discipline based on the knowledge of engineering acquired over number of years of study and practice.  Productivity analysis and Productivity Engineering in processes/operations are similar to Value Analysis and Value Engineering in case of components and products. Analysis provides the basis and engineering redesigns, develops,designs and implements the new element and integrates it into the existing system thereby creating a new system or modified system to gives better performance primarily in the area of productivity.

Productivity analysis may provide many ideas from existing knowledge base of library, current  trade materials, periodicals,  digital media content and internal employees as well as external consultants. Creative applications of existing knowledge will be suggested by one or other of the group of people involved in developing solution ideas. Each solution idea has to be evaluated for technical feasibility and economic benefit. It is important to mathematically optimize the solution idea and also evaluate its impact on operator's comfort, safety and health. Even test marketing may be necessary if it affects any feature or benefit that customer will notice and evaluate its impact on his utility and value.

There is management involved in implementing productivity increasing engineering or non-engineering changes in operations and processes.

October 2019

Tool Changing by Robots

Strausak recently automated the operation of its U-Grind machines by integrating Heidhain’s EQI 1100 rotary encoders on the six axes of an incorporated Staubli positioning arm. The robot is integrated into the machine enclosure but sits outside of the machine working area, giving operators unrestricted access for set up.
Removing the tool from the tightly loaded pallet, moving it to the tool holder, and inserting it also posed complex motion sequences for the robot arm. This process is executed—in reverse order—after the grinding sequence.
Automating this process would free operators during the machines’ long run times.
https://www.automationworld.com/home/article/15611759/machine-tooling-system-unveils-dramatic-productivity-increase

Norton Winter Paradigm
25 February 2019

A Game Changer for Precision Grinding of Non-Ferrous Materials

Combine the form holding and wheel life of a metal bond wheel with the dressability and free-cutting action of vitrified with Norton Winter Paradigm. Paradigm wheels deliver

Free-cutting with up to 46% natural porosity
Burn free grinding with high thermal conductivity
Truing and dressing on-machine in plunge or traverse modes
Made to your precise requirements with large ranges in specs available.

Round Cutting Tools

Increase productivity and decrease costs in manufacturing tungsten carbide round tools.

Thread Grinding

Superior corner holding with the industry’s fastest metal removal rates

Flute Grinding

Fastest cycle times and lowest cost per part. In-process truing capabilities

Gashing and End Teeth

Dress-free gashing and end-teeth work

Read the case studies
https://www.nortonabrasives.com/en-in/resources/expertise/norton-winter-paradigm


1/30/2018

Pallet Changer Increases Productivity of Grinder by Improving Spindle Runtime

The CVG series vertical universal cylindrical grinding machine with an optional pallet changer from Taiyo Koki Grinding Machine Company, a DMG MORI company,.

An  optional pallet changer can be used to load a new part on a fixture outside of the machine while the machine is running. Machinists can use a dummy spindle, which enables parts to be rotated and “clocked-in” at the part-loading station. This automatically selects programs and tooling for a different workpiece. Thus spindle time is not wasted to  run different jobs increasing  productivity and throughput.
https://www.moldmakingtechnology.com/products/pallet-changer-increases-productivity-of-grinder-by-improving-spindle-runtime-


December 08 2017

Coolant Change for Increasing Grinding Productivity 

On December 08 2017

Tests prove proper coolant produces higher gear grinding productivity -  David Graham and Philip Varghese, Application Engineering, Norton | Saint-Gobain

The grinding fluid/coolant provides lubrication and cooling that are critical to the economical production of precisely ground parts free of metallurgical defects. Additionally, it lowers abrasive cost by reducing wheel wear, aiding chip evacuation and protecting the machine from corrosion.

Inconel 718 (IN718) is the most frequently used nickel-based superalloy. Its  applications  are found in aircraft gas turbines, reciprocating engines, metal processing, space vehicles, heat treating equipment, nuclear power plants, chemical and petrochemical industries and heat exchangers.

Components made from this material can be  ground using conventional aluminum oxide based bonded abrasive grinding wheels.

Straight oils and water soluble oils are alternatives for coolant. Straight oils can be a blend of one or more of the different base oils (paraffinic, napthenic, synthetic and vegetable) and may contain boundary and/or extreme-pressure additives such as sulfur, phosphorous or chlorine compounds.  In water soluble oils, the concentrates sold by coolant suppliers contain 40 percent or more oil and are mixed with water at a ratio of about 5% to 15% to create the metalworking fluid. Selection of the coolant requires productivity analysis to select the one that gives higher productivity and lower cost.

The Impact of Different Fluids on Wheel Life

In order to determine the quantifiable impact of the type of grinding fluid on grinding performance and wheel life, engineers from Norton|Saint-Gobain Abrasives did a comparative study.  The results of the study proved that grinding IN718 in straight oil gave a 9–10 times improvement in productivity and in wheel life over grinding in water-soluble oil.

Testing consisted of grinding slots in IN-718 parts with half-inch wide wheels. For the  Two creepfeed grinding machine, wheel speed was kept constant at 8,500 surface feet per minute and coolant pressure was kept at 175 psi at a flow rate of 55 gallons per minute. An engineered, highly porous, ceramic aluminum-oxide-based grinding wheel specification, TG280-H20VTX2, from Norton Abrasives was used. Testing began with straight oil coolant and depth of cut per pass was set at 0.100" (2.5 mm). Work speed began at 10 inches per minute and increased in steps upto 180 inches per minute (254–4,572 mm/min).

A minimum stock volume of 2 in³ was removed under each condition. With the oil coolant there was never any evidence of burn/thermal damage. Subsequent metallurgical analysis confirmed no burn, and bent grains on the part did not extend more than 0.001" (25 μm) below the surface.


The test with WSO coolant began using the same 0.100" depth of cut used in the oil test. However, burn occurred at the first feed rate of 10 inches per minute (254 mm/min).

The test was changed. Specific material removal rates were,   the depth of cut was decreased as the work speed was increased. Specific removal rates of 1.0, 2.5 and 3.125 in³/min/in (10, 25 and 31 mm³/sec/mm) were chosen and table speeds between 6.1 and 300 inches per minute (2.6 mm/sec –127 mm/sec) were tested.

G-Ratio vs. Volumetric Material Removal Rate. G-Ratio, which is an indicator of wheel life, was significantly higher when grinding in oil coolant. Because rapid wheel wear was observed, it wasn’t practical to continue increasing removal rates when grinding in water soluble coolant beyond 5 in³/min/in (50 mm³/sec/mm). In grinding with oil coolant, removal rates as high as 18 in³/min/in (180 mm³/sec/mm) with minimal impact on G-ratio were  possible. This illustrates higher productivity, shorter cycle times and increased wheel life when grinding in oil.

When grinding with WSO, the occurrence of burn on the work pieces was still observed in some cases, and work speeds were varied to reduce or eliminate burn.

Summary:  In grinding IN718 alloy with a modern aluminum-oxide-based ceramic grinding wheel, both in terms of achieving higher productivity and wheel life, straight oil coolant outperforms water soluble oil coolant.

The actual performance and G-ratio values will be different for each grinding wheel and work material combination. Hence, industrial engineers and process planners have to experiment and find the right coolant for their operation.
https://www.nortonabrasives.com/en-us/resources/expertise/critical-cooling-gear-grinding-success

July 2016

7/18/2016

Norton Century45 high performance wheels  to improve the productivity of centerless grinding operations.

Saint-Gobain Abrasives R & D engineers have developed Norton Century45 high performance wheels, designed to improve the cost-competitiveness of centerless grinding operations.  The grinding wheels use ceramic, aluminum oxide and silicon carbide blends to grind barstock made from a variety of materials, including carbon steel, aluminum, cast iron, stainless steel 300/400 series, titanium, nickel alloys (Inconel) and copper.

The grinding wheels, with B45 vitrified bond, are specifically designed to yield better efficiency by achieving higher levels of stock removal per pass than conventional wheels—more than double in some cases.

Norton Century45 wheels are engineered for durability with maximum G-ratio and can last as much as twice as long compared with standard wheels. Fewer wheel change-overs result in less downtime, lower wheel inventory, reduced production costs and higher productivity.

Operation Improvement

The grinding wheel was introduced to improve the operation of a 40-hp Cincinnati Twin Grip centerless grinder, which is used for rounding and polishing Inconel barstock. Part OD was 0.5 inch to 1.75 inch and part length was 378 inches to 384 inches. The original 24-inch by 20-inch by 12-inch 80-grit silicon carbide resin bond wheel removed 0.005 inch of the Inconel alloy bar per pass. A Century45 two-wheel set—32CA60-PB45 (10 inches), 32CA80-PB45 (10 inches), with a removal rate of 0.012 inch per pass—was substituted in its place.

The new operation setup achieved  140 percent higher stock removal rate and 100 percent improvement in wheel life, resulting in a 50 percent reduction in cycle time. It also reduced noise levels during grinding (23.2 dB quieter than the incumbent). The new wheel demonstrated a total cost reduction of 30 percent over the incumbent wheel, resulting in an estimated annual savings of $98,800.

2. Operation improvement in  a 50-hp Cincinnati No. 3 centerless grinder used to round and polish the barstock of a variety of steel alloys, including 1045, 10V45, 4140 and 17-4.

Part OD was 3.5 inches to 7.5 inches and part length was 4 inches to 6.5 inches. A Century45 wheel—3NQAC36-S9B45—was selected to replace a 24-inch by 8-inch by 305-inch 46-grit aluminum oxide resin bond wheel.

The new wheel produced a 25 percent higher stock removal rate over the incumbent wheel (0.005 inch versus 0.004 inch per pass) and a 32 percent improvement in G-ratio. The net result was a 100 percent performance/cost improvement over the incumbent wheel.

Total cost reduction is the goal of all manufacturing organizations. On average, abrasives consumables only account for about 3% of the total cost. Machinery, labor, and overhead account for up to 80% of total manufacturing budgets ( The Norton Process Solution Program). The Norton Process Solution Program  (PSP) analyzes the cost, quality, safety, and service components of a grinding operation, with the goal of minimizing cost and maximizing overall productivity and safety.
Analyzing the grinding operation and improving its elements to  decrease the cycle time offers the greatest chance for return. With a 20% decrease in cycle time, on average, there will be a reduced total cost per part of more than 15%.

https://www.nortonabrasives.com/sga-common/files/document/Century%2045%20Article%20May%202016.pdf

https://www.nortonabrasives.com/en-us/resources/expertise/norton-century45tm-centerless-wheels

https://www.productionmachining.com/articles/abrasive-developments-for-centerless-grinding

May 2015

Intelligent Grinding System (IGS) for Higher Speed and Productivity at SKF

SKF engineers developed a solution to compensate for wheel wear that incorporated the latest advances in intelligent machine control, sensors, software, and process monitoring techniques.

The Intelligent Grinding System (IGS) incorporates a range of sensors and measuring devices supplying detailed data on the production process, including grinding power and grinding force, to a sophisticated machine controller.


This allows the system to assess the wheel wear and other process conditions continuously for each grinding wheel and to make automatic and instant adjustments to the settings of each machine in its plant. Thus,  every component is made with a unique set of grinding parameters but produced to the same set of finished quality parameters. The IGS produces consistent, defect-free parts at cycle times that are lower than the earlier times and thus giving higher productivity for SKF.
https://www.americanmachinist.com/machining-cutting/article/21898949/intelligent-grinding-combines-controls-sensors-and-process-monitoring

November 2014

Using Acoustic Emission (AE) Sensing Technology for Increasing Grinding Productivity

To increase grinding wheel life as well as time spent in wheel dressing.

AE sensing for grinding wheel developed by Schmitt Industries relies on the fact that when a grinding wheel touches a workpiece or a dressing wheel, even the slightest contact produces a sound that can be detected by sensitive instrumentation based on coolant flow.

Acoustic emission technology is so sensitive that it takes only a small number of grains of the wheels coming together to register a touch. AE sensors  supported by automated controls in a CNC machine can automatically perform functions such as grind detection, crash protection, gap elimination and dressing control.

Schmitt’s ExactDress  hardware/software product works with the company’s SB-5500 grinding control platform to automate the wheel dressing process by looking at the live acoustic emission signature of the dressing operation and comparing it with the profile of a known successful wheel dress to decide whether the wheel is dressed correctly or not. The guesswork and over-dressing of the wheel are eliminated improving quality while saving both time and cost. Users don’t need to replace expensive CBN or diamond grinding wheels as often as they have in the past.

https://www.productionmachining.com/articles/acoustic-emission-sensing-improves-productivity-and-prolongs-grinding-wheel-life

10.05.2012

GRINDING CELL COMPLETE REDESIGN IMPROVES CYCLE TIME BY OVER 62%

For  a manufacturer of air compressor rotors, Okuma and Gosiger Automation found a solution to improve the  efficiency and safety  of their grinding operation, Combining an Okuma GA-47 grinder with a single-handed FANUC robot with vision system and manually adjustable grippers, the new grinding cell reduced cycle time from 45 minutes to 16.8 minutes. The automated cell allowed one operator to manage multiple cells. It  provides more consistent throughput and increased safety and  comfort. An upgraded grinding wheel was used.

Okuma Grinding Cell

31 Jan 2012
Okuma America Corporation

http://www.okuma.com/americas
Automated Grinding Cell Improves Cycle Time for the manufacture of a compressor scroll.
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https://www.youtube.com/watch?v=CG-cXWqNdWQ
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https://www.okuma.com/grinding-cell-improves-cycle-time-by-over-62

https://www.okuma.com/grinding-cell-improves-cycle-time-by-over-62-1


NOV 30, 2003

Redesign of Coolant Nozzle to Increase Productivity

Thermal damage is detrimental to creepfeed grinding operation. The St. Gobain Abrasives' Higgins Grinding Technology-Center (HGTC) offers remedy to the problem using the company's Field Instrumentation System (FIS). FIS shows how the heat generated during grinding affects workpiece and process integrity and points out ways to optimize coolant flowrate, pressure, and nozzle design to produce quality parts.

An equipment manufacturer was having grind burn problems in  final surface creepfeed grinding of cutting blades manufactured of heat-treated 1526 hot-rolled steel. St. Gobain engineers reviewed the process. They conducted spindlepower measurements and audited the coolant-delivery system to check pump capacity, feed-pipe diameter, nozzle distance to the grinding zone, pressure, and nozzle design.

They took three 0.005-in. depth of cut and a final 0.003-in.-depth pass, using an electroplated CBN wheel with straight oil coolant. The coolant pump was a 15-hp multistage centrifugal pump with maximum pressure of 280 psi. Operating pressure, measured at the pump, was 120 psi due to large nozzle apertures. A 40-psi extinguisher nozzle quenched sparks from the grind.

Using the FIS unit, engineers recorded data for each pass for 15 parts. With each pass, the width of contact increased as more of the angle was ground. With the first pass, specific power varied significantly and was higher than with subsequent passes. This was from variation in the previous milling operation and part distortion during heat treatment. As the contact width increased during passes two and three, total power also decreased, resulting in lower specific-grinding power. They found that although the flowrate was adequate, coolant was not reaching the grind zone due to air entrainment caused by poor jet coherence and the air barrier surrounding the wheel, which deflected coolant. As a result, HGTC engineers designed a new coherent jet nozzle to match the higher wheel speed.

With the new nozzle, pressure at the pump increased to 170 psi. It was  estimated that a 20% drop in pressure between the pump and nozzle occurred, giving a jet velocity of  approximately 9,000 fpm. This amount was sufficient to penetrate the air barrier at the higher wheel speed. The wheel speed was increased by 20%, the removal rate increased 20%, with no evidence of part burn was found. Thus, the redesign of the nozzle led to removal of grinding burn problem and further increase in productivity.
https://www.americanmachinist.com/machining-cutting/article/21896614/system-takes-grindings-temperature