How To Choose Mass Finishing Equipment
For Surface Profile Improvement
Choosing any manufacturing equipment is like buying a new car. First you should decide what your needs are or how your vehicle is going to used. Next comes maybe performance and reliability followed by price. At any point during this decision process any one of these factors may influence the ultimate selection. That is, if one initially wants a sports car for performance, he maybe inclined to buy a sedan, if it can seat more people, gets a lot greater gas mileage, has a better ride, or lasts longer. Another big factor is the over all economics in the making of the final decision.
With mass finishing equipment, one normally never looks for a sports car, but is more inclined to buy some type of truck or bus for size. That is because most people are looking to process large size or volumes of parts. Normally the larger or more capacity of the machine system the better; however, speed, reliability, and accountability at a reasonable cost are all important factors. Some people are governed strictly by cost, which throws all good judgement and caution to the wind. That usually means trade-offs and/or temporary cures. Hopefully these people know what they are getting into and that normally means an under performing machine with a short life.
So, what makes up a good car or machine system? I think everyone will agree that a good motor is important for any mechanical system; however, with mass finishing systems it may even be more critical than with most other equipment. Why motors are so important is because they have to run in continuous duty over long periods of time and they do experience and have to overcome great energy forces that effect their life and over all performance of the system. Also, most of these machines operate in a harsh environment of dirt, dust, water, and experience a lot of side movement or vibration. The whole purpose of mass finishing machines is to perform abrasive tasks or material removal. That means that the processing abrasives have negative effect on all materials both inside and out of the equipment. Because of the energy forces generated, the motor and materials used in the construction of these machines have a tendency to want to self-destruct.
The best performing machines have ball or roller type heavy duty bearing motors with good end bells to house the bearings. Sleeve bearings and aluminum end bells are subject to distortion at high heat over prolonged usage, resulting in a much shorter motor life. Low amps or higher voltage normally ensures the motor will operate at lower temperatures and that prolongs the life of the bearings and motor. Also related to the selection of a motor is the horsepower. Like the comic Tim Allen and his former tv show Tool Time, the thought of "more power" is good to consider, because horse power also relates to the size of the bearings used in the motor. Good motor bearings, or larger the ball bearings used, the better. Normally the first thing to deteriorate with time and use are the bearings and that is mostly due to heat or frictional forces acting on the motor.
In mass finishing equipment, the motor can be mounted away from the work chamber or directly to it. Both systems have advantages and disadvantages. A motor can be connected to the work chamber with either a belt or coupling to ease the stress on the bearings; however, another transfer mechanism is involved and that is subject to slippage and higher maintenance. The other method uses a direct drive system and the motor is attached to the work chamber and experiences all of the forces that are transmitted to the work load.
Both systems transfer electrical power into a spinning mechanism that produces mechanical physical energy forces and that in turn is transmitted to the vehicle or work chamber. Energy transfer is not complete until it transfers that energy force into the abrasive, which then applies pressure and movement to the parts or product that needs surface profile modification. There is little or no difference in the performance of either motor mounting systems. The flexibility of a belt or coupling and the remote location of the motor normally improves the life, reliability, and maintenance of the motor system over that of a direct drive motor, but a direct drive system delivers more power and has fewer parts and better response.
Cars are made to look different every year now, but their internal parts and engine remains the same over a much greater period of time. In the newest or most recent model or version of mass finishing equipment called high energy, centrifugal system motors can use either a direct or indirect drive connection. This is the same option method also used on the slightly older technology of vibratory machine systems. High energy systems have to overcome inertia and that requires greater initial torque than vibratory systems, but otherwise they operate very similar to one another. Then again, the difference in the technologies or how the energy force is applied to the abrasive does make a big difference. The actual motor speeds of a high energy system and a vibratory system are the same, but the high energy system uses a gear reducer to accomplish a slower RPM than that used in vibratory. The energy force on the abrasive and the parts is greater and the processing time cycle is shorter, because the movement, spin, or RPM's within the work chamber or vehicle is greater than what occurs within vibratory equipment.
Vibratory equipment technology is designed to overcome a fixed amount of mass or constant eccentric weight that sets up a vibratory oscillation or spin to the contents within the work chamber and that movement maybe be adjusted. The motor systems run at the fastest RPM's of all the mass finishing equipment, but the contents within the machine run slower than the high energy systems. The motor experiences no resistance like centrifugal systems and they overcome the abrasive mass by transferring energy into a moving wave pattern of force. Just like the high energy centrifugal equipment, a vibratory eccentric weight mechanism can use either a direct or indirect drive motor system. Movement or rotation within the work chamber is also effected by the springs supporting the work chamber. The flexibility of the work chamber and the amount or position of the weight or weights in relationship to their rotation determines the amount of vertical lift the machine will produce and the horizontal travel of the contents within the work chamber. Normally the greater the vertical lift produced by the eccentric weight and springs the more aggressive the machine.
The third technology used in mass finishing systems is the old faithful, old fashion barrel tumbler. It is still being used and probably will continue to be used for many years to come. Again the motor system and connections are virtually the same as the other technologies so mentioned. Because the barrel systems use the slowest motor RPM's and the simple technology involved, their motors normally outlast those used in the newer mass finishing systems. Another fact to consider is the actual movement or abrasion within the work chamber is limited to the relatively small area within the work chamber known as the spill zone and that means that this is a very slow process with long processing times.
Now, how does all this information relate to the performance of the machine or vehicle? Well, the old fashion barrel tumbler technology is like driving from New York City to Philadelphia in a little over an hour versus the same amount of time to drive to Chicago using vibratory equipment and/or that same amount of time to reach Los Angeles using high energy systems. You might also compare this analogy to that of walking, driving, or flying. All these machines do the same thing; however, the time it takes to achieve the end results maybe a factor to consider and the type of transportation you use effects the way you want to travel. Time is only one of the costs that gets to your end destination.
Higher performance vehicles normally require better engineering, greater parts precision, and more time to build because the parts quality needs to perform better and safer than less precision systems. Faster machine systems require quality parts and materials that are designed to withstand more stress, pressure, and abuse than slower systems and that costs more. Simply stated, better parts build better machine systems. Hard materials such as metals are normally preferred over plastics for rigidity; however, flexible materials are preferred over rigid for abrasion and sometimes for chemical resistance; therefore the proper use of both materials are required to make a good mass finishing machine. What also effects the use of these materials is the size of the parts to be processed, weight, and the overall life of the equipment should also be taken into consideration to determine the proper cost of a machine system. Again, there are trade-offs.
The bottom line of most mass finishing systems is the motor, or not the former and current political slogan of "It's the economy stupid". Everyone looks to be fugal; however, to be thrifty in one place and not see the forest through all of the trees is another problem waiting to happen. The actual drive or energy transfer method from the motor is important, but not necessarily the most important factor. If it was, one of these designs would be dominate over the other. Probably, the fewer the parts, and the better quality the materials, and/or the greater the energy transfer the better the system. Speed of processing is a question that only the end user can answer and a lot of that depends on the volume of parts to be processed.
Another big factor to consider in the purchasing of a vehicle is from whom are you buying the vehicle or machine and the reputation of the dealer in offering a good price and servicing of your after market needs. You should know something about the company or people you are buying from as well as the manufacturer. The reputation of used car dealers is important and let the buyer beware is a must. Misrepresentation is ramped in this industry and knowledgeable people are few and far between. Most reputable companies will process sample parts and give you written explanations of how they achieved the end results. Some will also allow you to observe the actual equipment and the process in operation.
Warranties and replacement parts are another problem. All new machines should come with at least a one year warranty on parts and labor. One year is about the extent of the warranty allotted to manufacturers by motor manufacturers, so that is about the best they can do for you. After that, machine parts do wear out. The more you use them, the more they wear out and self-destruct. They are designed to work in a harsh abrasive environment and therefore, they do require maintenance and/or replacement parts. Replacement parts are another important aspect of working with a good dealer. You don't want to buy a machine system and find out you can't get service or replacement parts in a timely manner. If you are making a big investment, you should try to visit the manufacturer or distributor for the product you are considering.
Getting back to our car analogy. Now, a car needs fuel to operate. It converts liquid energy into mechanical energy. Some machines work better on a higher octane or diesel fuel than standard gasoline. All machine systems provide mechanical energy forces that support some kind of movement. In a car, the fuel is the media that provides power to operate the vehicle and the movement of the vehicle is the media form of transportation. It is the media that gets used and gets us to our end result or destination.
In mass finishing systems the media is normally a solid preformed abrasive or non-abrasive shaped ceramic or plastic, but it can also be organic in nature. What goes into the machine system determines what the appearance or how the parts come out of the machine. In addition to the media is the use of liquids, chemicals, and dry processes; therefore, you should again try to work with a reputable dealer to get the most out of your investment. Unfortunately, there are a 101 different chemicals and media that can be used and every form of abrasive and polishing media has a distinct quality of its own. With proper knowledge, the media can be just as important as the equipment. Good ingredients produce good results. Someone who knows all of the components can make a good system even better.
Media is selected to perform a specific function on a certain part and has a limited range of surface profile modification. No one size, shape, or composition will work on all parts. That also means that multiple step processes or different media maybe required to achieve the desired end results. The media is designed to break down and it becomes ineffective and/or increasingly inefficient as it is used. A good abrasive media will only last about 3 to 4 months on an average 40 hour week before it reaches what I call its half life. My definition of half life is self explanatory, it is half the size of the original preformed shaped media. At that size, it normally becomes ineffective on the parts it was originally intended to work. At that point, it should be replaced and the used material stored for much smaller parts or future use. It will not last forever and if it does, it won't work properly.
As mentioned, the after market or supply business and/or process knowledge is just as important and can be more so than the actual sale and operation of the equipment. There is a close relationship in this industry and equipment is just half of it. There are a lot of variables that effect the end finishing results or surface profile of a part. There is a big learning curve for this technology; therefore, I suggest you really consider who you want to work with in a close relationship, at least during a start up operation. It is in a sense, this is a marriage where two can benefit. All equipment systems, media, chemicals, and people are not equal; therefore, I suggest you choose wisely.
For more information, help or assistance, contact A.F.Kenton of Nova Finishing Systems Inc. 1610 Republic Rd. Huntingdon Valley, PA. 19006 or call 1-800-444-4159, or check www.novafinishing.com.
• Nova Finishing Systems Inc., manufactures small, heavy-duty bowl finishers that stack up to most of the big equipment on the market, but cost much less. Nova series vibratory equipment also comes with the same warranties of the larger machines. Form more information on this equipment line, contact:
PO Box 185, Hatboro, PA 19040 * 1610 Republic Rd. Huntingdon Valley, PA. 19006
215-942-4474 * 800-444-4159 * Fax 215-444-9982