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ACCU BEKAS: Maret 2009


Senin, 09 Maret 2009

Battery Rebuilding Manual & Supplies for Reconditioning:

The first thing that you must realize is that all batteries cannot be rebuilt. They must undergo a few simple tests to determine their present condition.
You will need some simple equipment and supplies in order to perform the required tests and to recondition the batteries:
1. A DC voltmeter.
2. An automotive battery load tester. It comes with full instructions from the manufacturer.
3. A battery Hydrometer.
4. A small electric drill.
5. A good quality battery charger.
6. A pair of homemade wire probes to clip to the test leads on your voltmeter. These are used to test each cell in the battery. They should be about eight inches long and can be made from brass brazing rod. This retards corrosion of the probes.
7. A plastic funnel to add the chemicals into each cell.
8. A supply of the China Depot battery treatment chemical to dissolve the buildup of sulfates in the bottom of the battery.
9. A stop drill bit to drill holes in the top of sealed batteries.
10. A supply of plastic plugs to seal the holes in the top of the batteries after repairs are completed. A good quality face shield to protect you eyes and face. NEVER WORK ON BATTERIES NEAR AN OPEN FLAME OR WHILE SMOKING. THE GAS FROM THE BATTERY CAN EXPLODE! ALSO, THE BATTERY ACID CAN BURN YOUR SKIN AND CLOTHING. Connecting cables to charge more than one battery at a time in parallel or in series if you have a series charger. Do not overload your charger.
This should cover your equipment and supply needs.
Now we will explain how to evaluate the battery for rebuilding or for scrap.

1. Place the battery on your test bench. Connect your load tester to the positive and negative terminals. The positive terminal is always the larger terminal and should have a + sign on it or next to it. DO NOT HOOK UP BACKWARDS AS YOU COULD DAMAGE THE LOAD TESTER. ALWAYS PUT THE POSITIVE LEAD ON FIRST AND REMOVE IT LAST TO AVOID DANGEROUS SPARKS.

2. Read the voltage shown on the load test meter. If the voltage is less than 12 volts chances are that the battery cannot be rebuilt. In the case of a six-volt battery it should read six volts. A battery that reads a volt less might bear further investigating. While the load tester is still hooked up you should perform a load test. Pressing the button on the tester and watching the needle does the test. Hold the button down for ten or fifteen seconds. If the needle drops like a rock and stays on zero the battery is probably junk. If the needle gradually climbs up to the yellow or green on the load test dial there is a good chance the battery can be rebuilt. Remember that each cell if it is working should read two volts. If the meter only reads ten volts total then you must have a dead cell. We don’t fix dead cells because we don’t take batteries apart.

3. One more set of tests that you can perform just to be sure is the cell test. We do two of them. One with a voltmeter and one with the battery hydrometer. If the battery has caps, pry them off. If it is sealed, drill the holes in the top of each cell with a stop drill so you won't hit the plates and damage them. Make sure all the cells have water covering the top of the plates. This could be the problem to start with.

4. Take the hydrometer and draw up the acid from the first cell. The scale that is marked on the hydrometer will tell you the condition of that cell. Make a note of the reading of that cell. Green is good, White is questionable and red is dead and probably will not come back with the treatment. Notice the color of the electrolyte while you are drawing the electrolyte from the cell. Draw it in and out several times so that you will disturb it and mix it up. This will give you a more accurate reading and also if the color is cloudy brown or black it means that the cell is in bad shape.

5. The voltmeter test is another very reliable test. Take the voltmeter and set in on the range that best reads out for twelve volts or six volts as the case may be. Clip the test leads onto each of the homemade brass probes.

a. Place the positive test lead on the positive terminal of the battery.

b. Stick the negative probe into the first cell next to the positive terminal. It should read approximately two volts. If it does not, record the voltage. Lower than two volts indicates a weak or bad cell.

c. Stick the negative probe into the second cell and stick the positive probe into the first cell that you just tested. Again, it should read approximately two volts. Record the voltage.

d. Follow this procedure right down the line to the last cell. REMEMBER THAT THERE IS ONLY A ZERO READING FROM THE LAST CELL TO THE NEGATIVE POST. Otherwise the total would be fourteen volts and not twelve. You have now pinpointed the low or dead cells in the battery.

e. If you consider the tests to indicate a marginal battery that might come back even though the test indicate it is junk you can perform the following procedure. Make sure all of the cells have water above the plates by at least one quarter of an inch. Add one tablespoon of the chemical reviver to each cell. Place the battery on the charger for one hour at a high rate of charge. Do not boil out the cells. After an hour you can then retest the low cells that you recorded. If they are reading two volts each you may then charge the battery at a low rate for at least twenty-four hours. It is more efficient to charge several batteries at one time on a low charge-using hook up cables. These may be obtained at an automotive supply store.

f. If the battery you are testing passes all of the tests you may then place it on the charger for a long slow charge. It is important to note that most of the batteries on the market today have lead calcium plates in them and when they get discharged down to a very low voltage they require a long slow recharge. YOU MUST ADD ONE TABLESPOON OF OUR CHINA DEPOT BATTERY TREATMENT CHEMICAL PURIFIER INTO EACH CELL TO DISSOLVE THE SULFATES THAT ARE BUILT UP ON THE PLATES.

g. After the battery has been on the low charger for twenty- four hours you should load test it and check the specific gravity of each cell with the hydrometer. All of the cells have to be in the green scale and the battery should load test no lower than the yellow scale on the load tester for a period of ten seconds. Follow the instructions furnished with your particular load tester.

h. The above procedures may seem complicated but they are not. You will learn them very quickly by experience. Do not be afraid to experiment with marginal batteries. Remember that you can load test them to be sure they are reliable and also, that you are giving your customer a twelve-month prorated warrantee on the unit. NEVER ARGUE WITH A CUSTOMER. GIVE HIM ANOTHER BATTERY OR GIVE HIM HIS MONEY BACK. Good customer service is the ONLY way to succeed in the long run; word gets around fast.

i. It is a good idea to save the electrolyte from the batteries that you junk. You may want to add some from time to time. This would be used in the case where you have a perfectly good battery but through someone's carelessness they wore a hole in it and you want to repair the hole and refill that cell. NEVER ADD ACID TO A BATTERY JUST TO SERVICE IT. YOU MIGHT BLOW IT UP! The best way to repair a hole in a battery is to use some fiberglass cloth and a two part epoxy resin repair kit. Just mix up the resin as per instructions and use it to glue several layers of the patch cloth over the hole. It is very important that you clean off the area around the hole with solvent that won't leave a residue (Denatured alcohol) and scratch up the case so the epoxy will stick better. Many a good battery has been saved with this procedure. Most of this is just common sense and always clean the rebuilt batteries with a mild solution of baking soda and water to neutralize the acid, and also clean up the terminals so that every battery looks as good as new.

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Minggu, 08 Maret 2009

A Realistic Definition Of Cycle Time

CNC Tech Talk

By Mike Lynch

Many people determine cycle time by measuring cycle start to cycle start time. As the operator presses the cycle start button, he or she starts the stopwatch. The cycle runs and eventually the machine stops. The operator removes the workpiece and loads the next one. As the next cycle is activated, the stopwatch is stopped. The elapsed time on the stopwatch, which includes load/unload, is the cycle time.
While the cycle start to cycle start time is very important, it does not take into consideration those things that do not happen in every cycle. Say, for instance, that you have a 1,000-part production run and the cycle start to cycle start time is precisely three minutes. Will your production run be completed in 3,000 minutes? Unless you've already perfected cycle time reduction for your company, it probably won't. It's likely the actual production run will take much longer.
What causes the difference? There are probably many things the operator is doing that do not occur in every cycle, but these add to the length of time it takes to complete the production run. Tool maintenance, warm-ups, machine cleaning, offset adjustments and even personal time are but a few examples.
Here is a more realistic—though admittedly more difficult to predict—definition of cycle time. Cycle time is the amount of time it takes to complete a production run divided by the number of acceptable workpieces produced. For lack of a better term, we refer to this measure as the throughput time. If our 1,000-piece production run takes 5,000 minutes to complete, throughput time is five minutes.

Too many companies place great emphasis on reducing cycle start to cycle start time, but they pay little or no attention to throughput time. It's not uncommon, for instance, to reduce cycle start to cycle start time by getting more aggressive with speeds and feeds, greater depths of cut, and so on. But the additional tool maintenance time caused by these more aggressive cutting conditions is often overlooked. In reality, attempting to reduce cycle time in this manner may not provide the expected benefit. In fact, increasing cutting conditions to reduce cycle start to cycle start time may even increase the time it takes to complete the production run if tool maintenance must be done while the machine is down.

We urge you to compare cycle start to cycle start time with throughput time for a few of your longer running jobs. You may be very surprised at the difference. It's not a bad idea to document both times right in your CNC program. It is not uncommon to find that throughput time is at least 20 percent longer than cycle start to cycle start time. We've seen it over 50 percent longer!

When it comes to cycle time reduction, target reducing the difference between throughput time and cycle start to cycle start time is a primary goal. Minimize the impact of tool maintenance by moving it off-line (when the machine is not running) or by making maintenance as quick and easy as possible for the operator to perform. Be sure operators have all inserts and other cutting tool components at their fingertips. Be sure operators know they can be making offset adjustments for the purpose of holding size while the machine is running. Machine cleaning and warm-ups can be done while the machine is normally out of production, such as during lunch, breaks or off-shifts. As you study your own cycles and compare them to throughput time, you'll surely come up with ways to save time.