Ceramic aluminum oxide wheels can increase the number of parts that can be ground between dressing routines, leading to centerless grinding cost savings.

Reducing overall production costs in today’s globally competitive market requires identifying all contributing factors and focusing efforts on the worst offenders. For example, in the fastener industry, centerless grinding is an operation in which process improvements can yield significant benefits. Oftentimes, fastener manufacturers opt to use low-cost abrasive wheels to reduce consumable expenditures. However, according to abrasive supplier Saint-Gobain, this strategy doesn’t account for a more likely culprit behind increased centerless grinding costs: non-value-adding wheel dressing time.

The microstructure of Quantum ceramic aluminum oxide has irregularly shaped crystals so wheels continuously expose fresh cutting points to a workpiece.

Low-cost aluminum oxide wheels require frequent dressing routines to maintain workpiece tolerances, surface finishes and production levels. Conversely, ceramic aluminum oxide abrasives, such as the new Norton Quantum line of grinding wheels from Saint-Gobain, can enable fastener manufacturers to realize more significant cost reductions by increasing the number of parts that can be ground between dressing routines.

Unlike conventional aluminum oxides, the microstructure of Quantum ceramic aluminum oxide has numerous small, irregularly shaped crystals that enable the wheel to continuously expose fresh cutting points. The company says this microstructure is even finer than other ceramic aluminum oxide grades such as seeded gel, meaning more points can be introduced to the workpiece. In addition, Quantum uses organic and vitrified bonds designed to optimize grain-to-bond adhesion and increase grain retention and wheel life.

Compared to seeded gel aluminum oxide shown here, the Quantum has smaller grains and more cutting points within a given area.

According to the company, grinding tests of nickel alloy fasteners have shown that Quantum wheels can complete three times as many parts per dressing routine than conventional aluminum oxide. This improved performance impacts the overall grinding process not just by lowering per-part abrasive costs, but also by reducing wheel dressing time by as much as two-thirds. Assuming workpiece grinding time for both types of wheels is the same, the total cycle time can be reduced by one-third.

Consider a production run of 10,000,000 fasteners. According to the company, centerless grinding machine cost constitutes the largest portion of overall fastener production expense, and wheel dressing accounts for almost 50 percent of that portion. If wheels require dressing after every 60 or 70 parts, the production run will include approximately 150,000 dressing cycles. If each of these cycles takes an average of five minutes, overall dressing time will take approximately 13,000 hours. Assuming a conservative, fully burdened labor rate of $60 per hour, that amounts to a nearly $800,000 expense for non-value added dressing operation, or about 38 percent of the total production cost.

This chart shows the total cost breakdown of centerless grinding of 10,000,000 fasteners using conventional aluminum oxide wheels.

However, because Quantum wheels require less total dressing time, they can provide a cost savings of more than $500,000 (26 percent) over the production run, the company says.

General Cutting Tools is an authorized Norton Abrasives dealer.  For more information, please contact us.

This chart shows the savings possible with Quantum ceramic aluminum oxide wheels.

Article From: 11/11/2011 Modern Machine Shop

Slowing a Fliesen tool as it moves across the wheel creates a closed wheel condition (abrasive grains are smoother, less sharp), a very helpful condition when trying to lower part surface finish readings.

You can count on Fliesen stationary diamond dressing tools. Open wheels (sharp, free-cutting abrasive grains are exposed) are created by increasing the speed a tool moves across the wheel. Open wheels maximize a wheel’s ability to remove metal quickly when grinding. Slowing a tool as it moves across the wheel creates a closed wheel (abrasive grains are smoother, less sharp), which is ideal when trying to lower part surface finish readings.

Are you dressing modern ceramic alumina grinding wheels? Our new Furioso plates and shank tools are made of the new generation of highly wear-resistant diamond blades, engineered to stand up to durable modern ceramic alumina grinding wheels, including Norton Quantum wheels. (see Furioso flyer in “Related Documents”.)

Norton No-Risk Test Policy
There is no better time to improve productivity in your abrasive operations. Saint-Gobain’s new No-Risk Productivity Policy is designed to help you improve any of your production goals including improved cycle times, lower total production costs, higher quality parts, or improved finish, while eliminating any risk. You define the metrics that determine a successful test as well as what is necessary to eliminate any risks, and our technical salesperson will identify the right product to help you meet your production needs, no matter what competive product you are currently using.

WHAT DOES NO RISK MEAN?

1. You have absolutely nothing to lose and everything to gain.
2. You define the application requirements and the metrics of a successful test.
3. You define the definition of No-Risk in terms of cost to test, downtime, part rejection, and any other risk that is important to you.
4. You define the time period of the test.

The Benefits of Fliesen Tools

Spend More Time Grinding
Single point, chisel, and cone point tools require operator attention to ensure proper tool rotation at regular intervals. Fliesen tools require no adjustments. Simply install the tool, dress the wheel to break it in, and the tool will do the rest. Operators spend more time grinding – rather than making non-productive dressing adjustments.

Longer Tool Life
Expect long life when using a Fliesen tool. Other stationary tools, made with a single diamond stone, develop flat spots (“wear flats”) over time – which create chatter and burn. Fliesen tools use hand-set, fine diamond grit, eliminating the creation of wear flats.

Reliable and Cost-Effective
Harder, H-bond metal formulation Fliesen tools have been specifically engineered to efficiently dress durable silicon carbide and ceramic wheels. Our new Furioso Fliesen tools have a unique bond system developed for optimal performance when dressing Quantum (NQ) ceramic wheels. W-bond Fliesen tools are designed for conventional aluminum oxide wheels.

Fliesen Tool Configurations

Fliesen tools are available in two basic tool configurations. The most common is a plate configuration, which is somewhat rectangular-shaped with a mounting hole. Fliesen Shank Tool configurations are plates mounted in shanks of varying sizes and shapes. Most grinding machines accommodate one or the other tool configuration. To find the correct tool configuration for your machine, check the existing dressing tool, refer to the Tools by Machine Type Index in this catalog, or consult your grinding machine manual.

MATCH THE CORRECT FLIESEN TOOL TO YOUR GRINDING WHEEL ABRASIVE
Use Fliesen tools with W-bond specifications for aluminum oxide wheels. W-bonded tools have the standard matrix of metal surrounding the diamonds. When dressing more durable abrasive wheels, such as silicon carbide and ceramic, use our H-bonded tools, or our new Furioso tools for Quantum and other ceramic wheels, which are harder and more durable. Markings on the tool indicate the tool’s bond matrix. Use the right bond matrix for your abrasive application, as each is specifically engineered to perform best on the abrasive it was designed for. The catalog product charts are categorized by abrasive and appropriate bond.

FLIESEN TOOL MOUNTING GUIDELINES

1. Be sure to mount the tool correctly. Tool contact surface should be perpendicular to wheel.

2. Mount tool with diamond on trailing edge whenever possible as shown below.

RECOMMENDED DRESSING PARAMETERS
There are three elements to proper dressing. Dresser Infeed is the amount of material the tool takes off per dress pass. Dress Traverse Rate is the speed at which the tool moves across the wheel. The third element is the Number of Passes across the wheel. We recommend the following:
1. Dresser Infeed
Dresser Infeed (amount tool moves into wheel) = .0005″ to .0015″ (.012mm – .038mm) for aluminum oxide wheels. Reduce by 25% when dressing silicon carbide or ceramic wheels.

2. Dress Traverse Rate
Select a Lead Value based on desired Surface Finish and run the formula below.

FINISH LEAD VALUE (PER WHEEL REVOLUTIONS)
For Coarse Finish (approx. 64 rms) .023″ to .030″ (.58mm – .76mm)
For Medium Finish (approx. 32 rms) .013″ to .022″ (.33mm – .57mm)
For Fine Finish (approx 16 rms) .006″ to .012″ (.15mm – .33mm)

DRESS TRAVERSE FORMULA:
Lead Value x Wheel Speed (RPM) = Inches/Minutes (mm/Min)

3. Number of Passes
One is required. Take more as needed to restore form or finish. Dress passes should always remove material from the wheel. If your tool is not cutting the wheel, it is dulling the wheel. Avoid dry or dead dress passes which do not remove wheel material.

MAXIMIZING TOOL LIFE AND EFFECTIVENESS
The goal of dressing is to maximize the wheel’s sharpness – for maximum metal removal when grinding. This is best accomplished through disciplined dressing speeds and feeds. Taking too much off per dress pass, and/or moving the tool too slowly across the wheel will cause the Fliesen tool to overheat, breakdown and wear prematurely. To maximize the tool’s effectiveness, increase the dress traverse rate as high as possible while maintaining part print surface finish requirements.

TOOL BREAK-IN
The diamonds in new Fliesen tools are often covered by the metal surrounding them and should undergo a break-in process before production dressing. This process ensures that the effective diamond layer is properly exposed. This is achieved by taking 3 – 5 dress passes at .005″ depth of cut (on wheel radius) at normal dress traverse rates.
Because the diamonds are set at a slight angle, it is normal for some diamonds to remain buried in the metal after the break-in and during production dressing.

COOLANT SPECIFICATIONS
Fliesen tools should be used with coolant whenever possible, to avoid overheating and shortening tool life. We recommend at least a .50″ (12.7mm) diameter stream of steady coolant be positioned so that the air barrier surrounding the wheel “pulls” the coolant (through the dressing action). A coolant velocity of 3% to 5% faster than the wheel’s surface feet per minute works well, or enough pressure to penetrate the air barrier surrounding the wheel as it spins.

RADIUS DRESSING CAPABILITIES
For most angle-head truing and dressing applications, Fliesen tools can provide uniform and consistent radius-generation second only to chisel and cone point type tools. When dressing very intricate forms, tool selection should be driven by the smallest concave or fillet radius needed to generate the desired radii, rather than wheel grit size. Refer to the chart below for radius dressing capabilities by diamond size.

By definition, truing ensures that the wheel is properly formed and that its spin is concentric to the mounting spindle. Dressing ensures that the abrasive particles are sharp during production grinding.

Each time a wheel is taken off a grinding machine, it must be re-trued. After production begins, the wheel should be occasionally dressed to restore its grains’ sharpness.

The rumors are true. Sharp diamond tools create sharp wheels, and dull tools produce dull wheels. Sharp wheels (also called open wheels) can remove the maximum amount of workpiece material during grinding. In lay terms, grinding with a sharp wheel is often fast and easy. By contrast, dull wheels (also called closed wheels) remove less material, often making grinding slow and hard. In addition to cutting less, dull abrasives literally rub the part and create smoother or lower surface-finish readings on the workpiece(s).

Sharp, open wheels are generally the preferred wheel condition. They tend to produce higher surface-finish readings and may require some intentional dulling to lower finish readings.

Creating an open (sharp) wheel is easy: Either 1) use a new stationary dressing tool or 2) move a tool – new or old – fast across the grinding wheel. Closed wheels simply require the opposite: 1) Use a dull tool, or 2) move the tool slowly across the wheel.

To ensure that your tools last a long time, pay close attention to some key parameters when dressing conventional wheels:

Wheel removal per dress pass. On aluminum oxide wheels, we recommend removing 0.001 inches (on the wheel radius) per dress pass. Reduce this amount by 25 percent when dressing silicon carbide or seeded-gel (SG) wheels, and reduce it by 50 percent when dressing Norton® Altos® (self-dressing ceramic aluminum oxide) wheels.

• Taking off too much wheel per dress pass overheats the diamond and often causes chipping.
• Taking off too little per dress pass, the sound of the dress to get louder, the finish tends to drop, and size/taper issues become evident.

The speed at which the tool moves across the wheel. Run tools using a single diamond at one speed across the wheel, and those using multiple diamonds three times faster. Remember, the slower a tool moves across the wheel, the lower the part’s surface-finish readings will be:

• For single points, chisels and cone point tools – Traverse Rate (the speed the tool moves across the wheel) in inches per minute = 0.006 x grinding wheel RPM*.
• For blades, grit (nib) tools and clusters – Traverse Rate (the speed the tool moves across the wheel) in inches per minute = 0.018 x grinding wheel RPM*.

* To calculate wheel RPM, divide Wheel SFPM (surface feet per minute) by (0.2618 x wheel diameter).

Avoid power dressing. If you need to reduce new wheel truing times, use an old tool as a roughing tool and save new(er) tools for production.

Creating Wheel Conditions

Open (Sharp) Wheel

• Generally preferred wheel condition
• Creates maximum wheel material removal
• Typically requires a new dressing tool
• Move the tool faster across the wheel
• Typically produces high finish readings

Closed (Dull) Wheel

• Wheel conditioning you may need
• Minimum wheel material removal
• Typically requires a worn dressing tool
• Move the tool slower across the wheel
• Produces lower finish readings

Choose NorZon BlueFire R887 for foundry, investment castings, and metal fabrication, or NorZon BlueFire R884 for foundry, primary metal, and wood/floor sanding.

Benefits

• Resists dulling
• Ideal for a wide range of applications and materials
• Longer life and faster cut rate
• More durable; stands up to demanding applications: high-pressure and hard to grind exotic alloys
• Improvement in base adhesion, reduced grain shedding
• Cool cutting
• The choice for grinding exotic alloys (titanium, etc.), forged and stainless steel
• Minimal loading
• Excels on soft metals (aluminum, brass, and bronze) and wood, as well as stainless steel and carbon steel

Features

• Premium, versatile, self-sharpening zirconia alumina abrasive
• New grain coating
• Improved Y-wt. polyester backing
• Upgraded resin bond
• Enhanced grinding aid in R887
• No super sizing R884

Cutting Tools Chicago aka General Cutting Tools is an authorized Norton distributor.