Centerless cylindrical grinding characteristics form

1. Two-wire External Grinding center hole does not play, do not support the workpiece thimble. Since the center of the workpiece uncertain, the grinding allowance is relatively reduced.

2. External grinding mill can not axially grooved workpiece, grinding perforated workpiece, does not correct the position of the hole axis, low concentricity of the workpiece.

3. Cut inside his cell under normal circumstances can only be processed on a roller rolling on the workpiece can therefore, particularly suitable for grinding sets of groups, and other thin-walled parts. Grinding sets of parts because the parts are positioning themselves cylindrical reference. Therefore it can not be corrected within the original uranium with external error between.

4. Centerless grinding time maneuvering and loading and unloading time coincidence, easy to implement grinding process automation, high production efficiency.

 

5. In the centerless grinding process, the change in position of the workpiece center depends on the size of the original error of the workpiece before grinding, process system rigidity, grinding, dosage and other process parameters (high workpiece center, pallets angle, etc.);

6 centerless grinding movement of the workpiece, the machine depends on the uniformity of the transmission chain, the workpiece shape, weight, guide wheels and supporting materials, surface morphology, grinding with a star and other process parameters.

7. Centerless grinding machine for a long time to adjust, to adjust the machine's technical requirements are also higher, does not apply to single and small batch production.

Grinding wheel introduction

Grinding wheel is a circular fixed abrasive tool, which is made of abrasive and binder. The characteristic of the grinding wheel is determined by the factors such as abrasive, grain size, hardness, bond, shape, size and so on. A wide variety of grinding wheel, according to the abrasive can be divided into ordinary abrasive (corundum and silicon carbide, etc.) grinding wheel and natural abrasive super hard abrasive and (diamond and cubic boron nitride, etc.) grinding wheel; Shape can be divided according to flat shaped wheel, bevel wheel, wheel cylinder, cup wheel, disc wheel, etc., and according to the bond can be divided into ceramic grinding wheel, resin grinding wheel, rubber wheel, grinding wheel, metal.

The characteristic parameters of the grinding wheel mainly include abrasive, grain size, hardness, bond, shape, size and so on. Since the grinding wheel usually work at high speed, it should be carried out before the use of rotary test (to ensure that the grinding wheel at the maximum operating speed, not broken) and static balance test (to prevent the work caused by machine vibration). After working for a period of time, the grinding wheel should be trimmed to restore the grinding performance and the correct geometry.

Advances in resin grinding wheel processing

Recently developed for the synthesis of binder alumina ceramic grinding wheels,with the less binding agent, and increases the porosity of the grinding wheel. The composition of the components to ensure the consistency and hardness of the structure.

Advances in resin grinding wheel processing

In the current gear grinding, still in use by ordinary abrasive. But the standard abrasive and aluminum oxide ceramic product productivity has been greatly improved. Sintered ceramic and single crystal aluminum oxide, synthetic binder, and the development of new grinding technology, this progress has contributed.

In the last 10 years, more and more people use powerful creep feed grinding mode processing involute. Compared with the hitherto conventional reciprocating grinding, grinding wheel contact area is much greater, therefore, the use of the wheel must be able to withstand high pressures. Only when subjected to a sufficiently high pressure on a single abrasive grit it may become a pointed.

Pneumatic Grinder Wheel Requirements

1, staff must wear a dust mask.

2, the use of grinding wheel workpiece, first start until normal idle, and then by the light and heavy get confide in prison, so that the force evenly. But the pressure can not be too large or bump violently, so as not to hurt broken wheel.

3, the workpiece when grinding wheel rotational direction on both sides allowed to stand, so as not to fire into the sand splashing wounding.

4, after the work is completed, close valves, the grinder placed into a dry safe place. So as not to damp wheel, then burst wounding.

5, pneumatic tools automatic shut-off valves should be kept intact to ensure that at the time of operation, only forced to start start to work.

6, pneumatic tools should be someone responsible for inspection, storage, regular maintenance.

7, prohibits casually start grinding wheel or something else beat impact wheel, when changing the wheel, check the wheel for cracks to pad level folder in prison.

8, not allowed to use unqualified wheel.

9, clean up, clean up with a brush to stop.

what type of abrasive The Grinding wheel is ?

Grinding wheel is the most important piece of a class of abrasive, then the following knowledge from the factory to talk about it grinding wheel:

Grinding wheel is to add a binder in the abrasive, the porous body through compacts made of dried and calcined. Due to the abrasive, bond and different manufacturing processes, characteristic differences between the grinding wheel is large, so the grinding process quality, productivity and economy have an important impact.

Characteristics of grinding wheel is mainly determined by the abrasive particle size, binder, hardness, structure, shape and size and other factors; abrasive wheel is the largest amount, the most widely used method of using surface rotating at high speed when used, can be of metal or cylindrical, round, flat face and a variety of other non-metallic type workpiece roughing, semi-finishing and fine grinding and grooving and cutting and so on.

The press can be divided into ordinary abrasive abrasive (corundum and silicon carbide) abrasive grinding wheel and the natural and super abrasive (diamond and cubic boron nitride grinding wheel) wheel; according to the shape can be divided into flat-shaped grinding wheel, bevel wheel, cylindrical grinding wheel , cup wheels, disc wheel and so on; press binding agent can be divided into ceramic wheel, resin wheel, rubber wheel, metal grinding wheel. The main parameters of the abrasive wheel, viscosity, hardness, binding agents, shape, size and so on.

In the production process to use diamond grinding wheel on the belt, the general grinding wheel is necessary to remove the cleaning operation for 5-7 days, there is grinding down rubber crumbs above, after the high temperature friction and firmly attached to the diamond surface, it is difficult cleaning.

Cleaning requirements: (1) to environmental protection, non-one can not be a halogenated hydrocarbon. (2) can not damage the diamond grinding wheel.

Safety matters in Surface grinder wheel using

Should be checked before using the machine automatically about whether homing lever, when actuated, about whether someone; grinding wheel is solid; the choice of surface grinder dedicated repair wheel dresser;

Before machining a workpiece, it should work to remove the burr of the workpiece and the working platform must be clean;

Wheel stops turning when not prohibited under the wheel rub working platform handling the workpiece; pre-processing, the disk is not flat;

After the work place, pay attention to whether the fixed magnetic suction; suction magnetic movable workpiece, the application stoppers fixed;

When the grinding wheel, workpiece or not put items not related to work on the platform;

When the machine automatic feed, the operator will be allowed to leave their jobs or doing unrelated things; unavailable items beat internet; work which must be handled with care; cleaning the machine, do not use air gun wiping; machine per job 1 hour, hand pumps required to guide oil plus 1 times.

3.2 grinding operation procedures in strict accordance with the operation (1) the operating handle or button must be carefully checked before driving is in the correct position, the movement of the grinding machine is normal. (2) grinding wheel should be the first to the installation of new work for idle running speed. Idle running time is: A. a diameter of 400 mm, or more, idle time is greater than 5 mins, B. diameter < 400 mm, the idle time is greater than 2 min. (3) check carefully before grinding by grinder piece in card is correct, tighten reliable, special attention should be paid to adjust stop position, and tighten, pay attention to prevent collision grinding wheel chuck, chuck or top. (4) grinding, should in the workpiece and grinding wheel is under a state of normal operation and feed (feed may not be too hard); Also, must be in after the blade to stop.

3 How to prevent the occurrence of broken wheel in use
Broken generally due to incorrect installations can lead to discontinuity in the high-speed rotating grinding wheel gradually cracks caused by the grinding wheel occurs during use or during the grinding crash due to improper operation caused.
3.1 strictly required to install the wheel
(1) caught in the wheel of the wheel on both sides of the chuck, its shape, size should be the same.Diameter (2) flange mounted generally half the wheel diameter (minimum wheel diameter of not less than one-third), the inner surface have a groove.(3) grinding wheel and the wheel chuck contacting portion should be kept clean and smooth.
(4) with the wheel and the wheel chuck hole between not too tight, nor too loose, it should be placed at random.
(5) shall be accompanied by a compressible material (such as elastic cardboard, leather, oil and rubber, etc.) between the grinding wheel and washer made wheel chuck having a thickness between 0.5 to 3mm (better compression material thickness thicker ), is larger than the diameter of the outer diameter of the wheel chuck 2 a 4mm.
(6) should turn symmetrically tighten the screws on the wheel on the chuck (if a plurality of compression screw and tighten when the order shown in Figure 4), the clamping force evenly distributed, but not excessive force, preferably measured Torque wrenches the clamping force of each screw similar to prevent local excessive stress. This requires the grinding wheel in the ditch and install double-end mill is particularly important.
(7) installed on a multi-piece wheel chuck wheel, allows the use of a spacer between the separated wheel. Wheel diameter and clamping surfaces must be equal to the size of a spacer and the wheel chuck. We specialize in the manufacture of bonded grinding wheels allow or stacked installation. Some outer groove cut into the grinding process does not require the operator in the case of wheel sizes available, there had been unauthorized use of two stacked thin wheel alternative, which is a serious violation of the provisions practices must stop.
(8) is greater than or equal to 200mm diameter wheel mounted on the wheel chucks should be static balance (center of gravity balance method, three-point balance method). If not balance method of installation, you should check the radial wheel runout, deflection is too large, you should re-install the wheel.

2.3 carry out a check prior to installation of the wheel

2.3.1 Safety line speed wheel

In order not to cause errors, it is printed with safety signs on the wheel speed, especially in high-speed grinding wheel should be more eye-catching special signs. It must be used on the operating speed of the grinding wheel flag operation.

Currently in the process of bearing outer groove, the groove cut grinding step most people are using the high-speed wheel (50 a 6 0 m / s), centerless grinding, inner diameter grinding (Ha axis use the high-speed wheel), bis face grinding processes are generally used linear velocity of 35m / s wheel. Operator in previous work, have occurred outside the raceway grinding process without violation of the provisions originally should 12000r / min grinding wheel spindle speed adjusted to 18000r / min, due to causes beyond its safe wheel speed using broken lines occur .

2.3.2 Visual inspection (visual inspection)

. A wheel should be kept dry, clean, and not stick a foreign body;b. must proofread its safe operating speed for identity is unclear or unmarked wheel must be strictly prohibited.

2.3.3 Check percussion (sound check)

Vitrified grinding wheel before use this check. In practice there are many new workers to tap inspection methods do not have, not even this check, stay hidden for the occurrence of broken wheel.

The correct way to check is to be inspected abrasive placed securely (in the case of small wheel, finger caught, large size can be placed on hard ground.), With 200 300g of a rough wooden tap lightly tap points on either side of the wheel, perpendicular to the center line on both sides of 45 °, from the outer circumferential surface of the grinding wheel 20 at a 50m m (Figure 3), after the percussion wheel rotating 45 °. Repeated once. If the wheel is no crack crackled, used with permission. If you happen voiceless sound muffled or not allowed to use.

2 How to prevent broken wheel occurs at idle

Grinding procedures in both a requirement that the operator should be allowed to idle for a few minutes before making a new installation of the grinding wheel, its purpose is to look at the possibility of their broken. The reason why wheel broken occurs when idling, mainly because it had been before the rotation of a crack, so to prevent such occurrence should prevent the wheel broken cracks in the transport, storage and installation.
2.1 right wheel mode of transport, methods
(1) long-distance transport: a complete package when handling, no significant impact on the environment available soft material wheel fully tamped to prevent removal during vibration and shock effect.
(2) short-distance transport:
. A wheel when moving to prevent falling or being hit and striking impact such action;. B You must roll handling, to spread to cushion wood, rubber, or other types of straw bags, gently rolling in on the ground;c. Special wheel weight should be used in handling special handling tools, tools should be used with a soft liner material, vehicles should be equipped with pneumatic tires.
However, in real work, we can often see short-distance transport wheel officers without taking any protective measures, the way the plant scroll wheel, wheel carts with solid transport wheel (especially the groove cut grinding wheel), transportation and storage of these acts are disregarded provisions wheel, the operator's personal safety irresponsible for accidents potential problems.
2.2 Correct wheel storage method
(1) Storage environmental requirements:
. A wheel should be stored in a dry, small changes in temperature and the room temperature should not fall below 5 ℃ in place;. B no vibration place;. C rubber bonded grinding wheel is not in contact with the oil, resin bonded grinding wheel should not be in contact with a base;d. rubber bonded grinding wheel and resin bonded grinding wheel storage temperature, preferably 20 persons 5 ℃, relative humidity should not exceed 60%, to avoid direct sunlight and heat close to the local drainage device.
(2) storage space requirements and the way
. A wheel should not be piling up at random, should be stored in the appropriate bracket, cupboard or drawer, the specification should be a separate place, there shall be deposited mark in order to avoid confusion and errors;b. The method should be placed depends on the shape and size of the wheel, thicker or larger diameter wheel should be placed upright or tilted slightly thinner and smaller wheel should be placed flat stack, but do not exceed the stack height 500 a 6 0 0mm;. C small diameter grinding wheel (Ф50 mm or less) can be used rope to string together custody, bowl, cup-shaped, and butterfly wheel should be stacked one by one down the bottom surface, but highly placed not too high;d. rubber or resin sheet wheel stacking height To 2 0 0mm or less, and a flat iron plate and put in its top and bottom, to prevent deformation of the wheel, the wheel with the sharp edges of the sheet to be stacked in the middle of the pad to pad (thick paper or other soft material);e. resin binder, rubber bonded grinding wheel storage process, the binder will reduce its strength to aging, so the shelf life of such grinding wheels generally can not exceed one year. Wheel must exceed the storage period after re-examination in order to use;

How to balance the grinding wheel?

Grinding Wheel is one of the most commonly used mechanical plant equipment to the product, its installation is reasonable, safe and correct use of and compliance with safety procedures, etc., this series of problems are directly related to the security of each operator Therefore in practical applications we have enough attention.
Installation inaccurate result does not coincide with the center of gravity of the rotary shaft of the wheel, the wheel face in this difficult balance, to manage the balance of the face, please refer to the following recommendations:
Grinding Wheel Face unbalanced performance has two main aspects, the vibration caused by high speed rotation of the wheel, causing the workpiece surface polygonal chatter; on the other hand mainly in the imbalance accelerated spindle vibration, bearing wear, and in severe cause wheel breakage.
So to go through plastic wheel trim can only be used if found Face imbalance should be promptly repaired. Prevent wheel end surface of the inner end collision, so be careful to adjust the table to the left stopper.
Adjustment is done in accordance with the length of the hole on the next major axis mark, in the case of non-rotating grinding wheel and the workpiece, first with the left stopper coarse table travel, then stop screw iron on trimming, reaching into the end face of the pottery wheel workpiece undercut after the reverse.

Three problems should be noted in replacing the grinding wheel

Grinding wheel is one of the important tools for grinding, grinding wheel after the time used for a long time, probably there will be some problems, so to replace the grinding wheel, replace the wheel there are some considerations, what are these considerations is it? Next, we take a look at it!

Grinding Wheel Replacing Wear problems:

Any wheel has its requirements for the use of certain wear, wear reaches a certain level must be re-replacement of the grinding wheel. Not in order to save material, it requires the use of ultra-wear, which is a very unsafe violations. A general rule, when the wheel wear to diameter ratio of diameter 10mm chuck should be replaced with a new wheel.

Grinding Wheel Replacing Validity problems:

The new wheel from the Treasury brought out is not necessarily qualified wheel, new wheel even buy from the manufacturers are not necessarily qualified wheel. Any wheel has its certain expiration date, under the terms of use, which is qualified grindstone; use over the period, it is not necessarily qualified wheel. Rules of "the use of the grinding wheel should be within the validity period, resin and rubber bonded grinding wheel storage must be approved by turning test, those who pass the testing after one year."

Grinding Wheel Replacing Texture problems:

During using, if you find a local wheel cracks, stop using it immediately, replace the new wheel, wheel to avoid crushing injury accident

In the grinding process when grinding hard metal, should be used in a softer wheel. Because when the wheel is easy blunt, in order to timely self-grind, you should use a softer wheel. On the contrary, when grinding a material slightly soft, slow sand passivation, should choose a hard grinding wheel, in order to maintain grinding performance. But in grinding very soft materials, such as metals, due to chip clogging wheel easily, it should be used a softer wheel.When coarse grinding, grinding force and sand, easy self-grind, it is optional medium hardness of the wheel; high speed grinding wheel from poor grind, grinding wheel hardness than the average level of 1 to 2 hours.Molding grinding wheel in order to maintain the correct shape, should choose a harder wheel; machining a discontinuous surface, due to the impact of sand easy to fall off, you can choose a harder wheel.Poor thermal conductivity, easy to burn the workpiece, such as high-speed steel cutting tools, bearings and other applications softer wheel. Hollow and thin-walled parts, difficult to heat and easy to burn, use a softer wheel.When the grinding machine stiffness, with a softer wheel with the wheel hard and has low stiffness vibration. Large grinding area, you should choose a softer wheel.

The metal sintered centerless grinding wheel

Metal bonded grinding products with high efficiency, Good self-sharpening wheel, allowance, strong grip on the abrasive ability, wear resistance and other characteristics.

Products Introduction

Features: Metal bonded grinding products with high efficiency, Good self-sharpening wheel, allowance, strong grip on the abrasive ability, wear resistance and other characteristics.

The main target: Processing of optical glass, crystal, glass, precious stones, agate, sapphire and other materials.

Productions of sintered metal wheel products are: sintered centerless grinding wheel, cylindrical grinding wheel, grinding wheel periphery, bronze cutting, sintered bronze disc ,etc.

Juchuang Abrasive offers a variety of bronze bonded grinding wheel.

Diameter range: φ10-500mm, Thickness Of Wheel: 0.5-400mm, Grit size: 30/35-w3.5, offer the special wheels as customer’s requirements.

Different ceramic grinding wheels with different hardness

Different ceramic grinding wheels have different hardness, so we use to choose the right wheel. If the ceramic wheel wear too fast, specific instructions for processing rolls chosen ceramic wheel too soft, you can take the following improvements:

Ceramic wheel increase line speed, improve carriage longitudinal feed rate per revolution of the workpiece pallet namely longitudinal feed of the grinding wheel to the width of the 2 / 3-3 / 4; reduce the roll speed. If these measures have not yet achieved significant grinding effect, indicating pottery wheel too soft, does not apply, should choose a little hard ceramic grinding wheel.

If the grinding roller midnight, pottery wheel was blocked or dirty difficult, not falling sand passivated, wheel adhesiveness debris grinding roller surface burn appeared, galling, then the selection wheel too hard, you can take the following measures to improve. Reduce the ceramic wheel speed and improve the speed of the rollers.

Resin grinding wheel processing

Wheel is one of the grinding apparatus is widely used, a wide variety of grinding wheel, grinding wheel different role is not the same, here we want to introduce resin grinding wheel application, take a look at it!
(1) with a resin grinding wheel or on cylindrical grinding machines Universal grinding machines for cylindrical surfaces, conical surfaces and the shoulder end of shaft, sleeve and other types of parts were grinding.
(2) with the end face of the outer circumferential surface of the resin wheel or wheel, such as wheel bolt, large pores wheel, wheel slot, the use of cup-shaped grinding wheel, cylindrical grinding wheel end surface porous and porous wheel grooved wheel, and the like, a variety of mechanical parts straight to meet the flatness, the mutual positional accuracy between the surface roughness and plane and other requirements to perform plane grinding.
(3) with the outer surface of the resin or resin grinding wheel, including grinder, universal grinder or on a dedicated grinder, high quality requirements for surface through holes in the blind hole, stepped hole, tapered bore and bearing channel and other components for internal grinding process.
(4) The resin wheel, resin and rubber guide wheels in centerless grinding machine, using flexible positioning mode, use the wheel outer circumferential surface of the inner circle or outer surface of rotationally symmetric centerless grinding.
(5) with a special resin grinding wheel screw wheel. On the thread grinder, high precision and surface roughness transmission thread, thread measuring parts, tools and hardened screw threaded portion of the threaded processing. Such as threads, worm, tap, hob, gauges and other grinding with tapered thread, long thread, parallel threads and the like.
(6) with an epoxy resin honing wheel and double cone, butterfly, Shuangdie type, worm grinding wheel, the gear grinding machine for through hardened gears Gear grinding.
(7) with a strong resin grinding wheel, the grinding tool, having high hardness hot hardness, wear resistance and sufficient strength and toughness of the cutting tool materials, such as carbon tool steel, alloy tool steel, high speed steel , carbide, etc., were grinding tools, in order to achieve the desired accuracy, surface roughness and correct geometry, so that the cutter blade with high sharpness and durability.

The important role of binding agent in the manufacture of grinding wheel

Binding agents may be attached to the abrasive wheel using a variety of materials, and the nature of the type of binding agent directly affects the grinding wheel hardness, strength. Since the grinding wheel grinding carried out in high-speed rotation, and is in high temperature, high pressure, high impact loads as well as under conditions of strong corrosive fluid cutting work, so the strength of a solid abrasive paste, binder itself heat, corrosion resistance , has become an important requirement for binding agents.

Commonly used grinding wheel bond the following three:

Inorganic binder, commonly used ceramics.

Organic binding agent, commonly used resin and rubber.

Metal binding agent for part of the diamond and boron nitride grinding wheels.

For example vitrified, with its bonded grinding wheel, its stable physical and chemical properties, the gap more, can better maintain the geometry of the grinding wheel, cold, hot, dry, wet adaptation, and are not afraid water, oil, acids, alkalis, the price is cheap, so widely used. But the use of vitrified bonded grinding wheel brittle texture, lack of flexibility, can not withstand the impact of large and twisted side pressure, not manufacturing thin grinding wheel peripheral speed of the grinding wheel is generally only 35m / s or less. Each binder has the advantages of its use, the user has the choice of targeted, in order to play a role in a full range of applications.

History of Grinding Wheel

Everything is step by step developed from the wheel is no exception, and the wheel is how it evolved? I do not know, right? I do not know to look down with me! Mastered the history of the grinding wheel, the wheel for the purchase and application are beneficial.

As early as the Neolithic Age, humans had already started to use natural millstone processing knives, axes, bone, horn, and tools such as a tooth; a long time ago, humans have found a natural abrasive and clay combination firing ceramic wheel; 1900, the advent of artificial abrasives, using artificial abrasive wheel manufacturing all kinds have been produced to create the conditions for the rapid development of grinding and grinding machines. Thereafter, the abrasive grinding wheel gradually increase the proportion.

At present a lot of production of metal products in the world, therefore, belongs to the hardware industry category wheel naturally played a crucial role in strengthening the wheel of production process innovation, improve production technology, product innovation capability of enterprises to open restricted and enterprise technology level "bottleneck" in a timely manner the new grinding wheel used in existing equipment business, extending its technical life, enhance its effectiveness in the production source to ensure product quality.

As in recent years, China's rapid economic development, technological innovation of the wheel has been strengthened in the future it will become China Abrasives category accounted for the largest product category, and because of the unique advantages in the grinding wheel industry chain late, great to promote the application of the polishing wheel in. According to the analysis, to 2015, China will surpass France as the world's largest abrasives market, initial estimates, our products will occupy abrasives Abrasives world demand for additional products 3/5, as abrasives and grinding wheels one of the major product categories, is also facing a good development situation.

Saw cutting Grinding wheel Somatic

Effect wheel caused by unqualified

Wheel failure may have a variety, we also know some, and some we did not know, today we come to know the contents of some of the failed wheel, such as hardness failed, face runout, radial runout failed, and apertures substandard, let's take a closer look at it!

      1) Hardness failed

      Wheel hardness refers to the binding agent from the abrasive wheel surface resistance from the resistance in the external force, or the degree of difficulty understanding the abrasive wheel surface detachment. Hardness can more accurately reflect the performance of the grinding wheel, the wheel is an important indicator of quality. Wheel hardness of the assessment there are two requirements:

      Uniformity of hardness (hardness measured value of each point difference between maximum and minimum value) to comply with the provisions of the standard;) meet the hardness requirement that the arithmetic mean of the average value of hardness (hardness measured at each measuring point value ) to allow standard within the range. The proportion of unqualified hardness is quite high, such as flat-shaped grinding wheel hardness failed in more than 20% of its total failure.

      2) face runout, radial runout failed

      Face runout, radial runout failure would affect the balance and produce yaw performance, adverse impact on the machine tool and the workpiece when the wheel rotates, it should be controlled within the allowable range.

      3) failed aperture

      Wheel bore is to install the base, the aperture wheel failed as a "heavy flawed" in the standard. Large aperture, the eccentric wheel to generate after installation, so that the grinding wheel imbalance will increase high-speed rotational vibration, affecting the quality of grinding, grinding wheels and even lead to rupture, damage to the equipment. Pore ​​size is too small, not installed on the wheel can not be used, if forced to install, then scratch the spindle, the wheel can also make a dark wound, causes a rupture running wheel, easily lead to accidents. Aperture failed in the case of checks of the most serious. 16.7% of the total failure of the flat-shaped grinding wheel, wheel-shaped cymbals accounted for 58.2% of the total failure.