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PRACTICAL MANAGEMENT OF METALWORKING FLUIDS

Mark Dunwoody, P.E. Senior Manufacturing Engineer

The Torrington Company Clinton, SC

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PRESENTED AT: "Metalworking Fluids" March 12-14, 1991 Dearborn, MI

SPONSORED BY: The Society o f Manufacturing Engineers Courses and Clinics Department One SME Drive, P.O. Box 930 Dearborn, MI 48121-0930 Phone: (313) 271-1500 FAX: (313) 271-2861

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1989 a

MR89-455

Practical Fluid Management

author MARK E. DUNWOODY Senior Manufacturing Engineer The Torrington Company Dahlonega, Georgia .

abstract This paper establishes the objectives of a progressive fluid management program and provides the reader with the laols necessaty for sound Nuid management. I1 avers lluid management of individual machine sumps. depments. or entire facilities. Step- by-step procedures are given Io obtain the steady state conditions necessary for obtaining lhe highqualilyhigh-produaion levels necessary in today’s manufacturing environment.

conference Metalworking Coolants Clinic March 28-30, 1989 St. Louis. Missouri

index terms fluids Cleaning Corrosion Prevention Grinding Cutting fluids

Society of Manufacturing Engineers One S M E Drive P 0. Box 930 Dearborn. Mlchigan 48121 Phone (313) 271-1500

INTRODUCTION

The management of metal working fluids is extremely critical to obtaining the high quality/high production levels necessary in todays manufacturing market. objectives of a progressive fluid management program and provide the reader with the tools for fluid management. Step by step procedures will be presented to walk the reader through an overall Plan for such a program. These steps will consiat of:

This paper will establish the

1) Identification of problem areas. 21 Understanding and organization of reiources. 3 ) Development of a management plan. 4 1 Implementation of the management Plan.

These steps can he followed for f l u i d control systems for an lndividual machine, a d e o n r t . m r n t 0 - e - - -- --*‘-- *--” ’ -

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SME TECHNICAL PAPERS

This Technical Paper m a y not be reprod& in whole or in pan in aiy form including nuchlne-madable abrtrac:. without prmrrrton lrom the Society of Manufactunng Engineen. By publuhing thu pawl. S M E d c a not provide an endoncmcnc of producu or Y N I ~ ~ which m y be ducuued in the paper's conicnu.

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- Any drums stored outside? - Any fluid leaks? - A 1 1 fluids correctly labeled? - All fluids used for correct purpose? - fire quantities of fluids measured correctly? - Are fluids correctly mined? - Do operators know what fluid is in use? - Do operators know what concentration the fluid is supposed - Do operators know what concentration is now? - Do operators know how to correctly add makeup? - What contamindnts are getting into fluids? - Are waste streams being kept separate? - How close are concentrations controlled? - How often are systems cleaned? - How often are systems recharged? - Exactly why are systems recharged? - How many different fluid venders are there in'plant? - Who are these venders?

to be?

Other areas that need an investigation:

- What is water quality? - ,How does water quality change? . - Who uses how much water and when? - A review of all the liquid waste leaving the plant. - A complete analysis of the waste treat facility. - Fluids leaving the facility through other means such as

through HVPC units. swarf, chips, empty drums. or o n your product need to be considered. - Is recycling o f fluids feasible? - What is the vender support for each fluid? - Does each vender know and understand what you are

- Are they knowledgeable about their products? - fire they knowledgeable about your process? - Do they really solve your problems? - Do they understand the interactions of their fluid with

contaminating their fluid with?

other fluids i t comes into contact with?

Major issues such as poor tool life, rust problems, size control, poor surface finish. and similar problems should dl50 be addressed. The table on the following page is an example o f how major issues can be tabulated to assist in addressing fluid management needs. The specific concern will depend on one's individual situation.

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The most important aspect of fluid management is obtaining a steady state condition of the fluid system. The more consistent the fluid and its system the better you can run your operation. If irreversible progress in an operation is to be accomplished through fluid management, then the systems and fluids must be in a steady state condition at all times. This relationship is actually a closed loop with each component highly dependant upon each other.

II PIONITORING AND CONTROL +

- STEADY-STATE

- PROCESS IMPROVEIIENTS

A s monitoring and control are improved# the system comes closer to a steady state condition. A s the system comes closer to this condition, it performs more consistently enabling process improvements to be made. These improvements must then be monitored and controlled to achieve a new steady state condition. If this relationship breaks down because of insufficient monitoring, then the loss of a steady state condition will lead to the loss of the process improvements. This results in a downward deterioration o f the system. Improvements become fewer and more difficult to achieve. This downward deterioration is broken with a fluid management plan. A s the implementation progresses, a continual improvement in quality and productivity will be realized.

FLUID RANCIGERENT ORGANIZATION

Identification of problem areas - The starting point for any successful fluid management program is a complete cost analysis and a complete investigation Of all Of the relevant fluids and their uses. This is first done by examining purchasing records over the last 12-36 months. Often this review will immediately reveal some obvious areas o f needed improvement. Scrap and rework records due to fluid related problems need to be conducted. A walk through inspection of the plant needs to be conducted to observe the following type of situations:

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the fluid. If there are any unknowns in your coolant, cleaner, rust preventative, plating solutions, or fluid under consideration, or you do not understand how it varies over time, then you are working in the dark. As you are obtaining steady state conditions ask yourself leading questions such as: Is that change in tool life a result of the concentration changing? Is it because of a cleaner fluid? Is it because of more flow to the tooling? Cooler fluid? Is the rust caused by the coolant itself, or was it from the department before? Is that fluid that looks dirtier actually dirtier? By how much? Is it effecting the process? Why did it occur this time? These are just a few of the on-going questions that must be answered to guide you toward obtaining steady state conditions. This will then lead to true irreversible improvements in quality and productivity.

An example of taking a fresh look at a proces's beginning with the basic premise of monitoring and control is shown by an eyelet press operation consisting of 12 large presses. They had been operating for years with a heavy duty water soluble drawing coolant. There was no organized method of concentration control, and most operators did not really know what concentration to run. Most did not even know how to check the concentration. With the implementing o f simple control methods and monitoring, the department saw tooling costs cut dramatically as well as substantial reductions in fluid related costs. Simply by addressing the concentrate control methods tremendous cost savings were obtained.

Another plant was sporadically plagued with rust problems which threatened to shut down their Customer. What was needed was a fresh approach to the problem. When the coolants and cleaners themselves as the culprits were exhausted, a check of the incoming city water was conducted. I t is hard to believe that the method used by the city to add chlorine to the water supply was resulting in chlorine levels many times higher than allowable. It was about the same as using swimming pool water for all of the makeup water. From that point o n a regular monitoring o f incoming water was conducted to .Assure the condition o f the fluid.

Parameters such as flow rate of a fluid to the work piece must also be carefully evaluated. Everyone normally considers the fluid to be on or off. But what about the one operator that is adjusting the flaw for size control? Is he sacrificing tool life? Is this the reason for the bed o f the machine to be clogging up with chips and sludge? O n several occasions this has been the case as well as wide size variation. This example shows the importance of flow meters and pressure gauges o n coolant nozzles.

6 final example was demonstrated in a centerless grind operation. Two 12,000 gallon coolant systems were being dumped about every four months. Different attempts were made to solve the high rate OF dumping but no progress was being made. It was not until the system was monitored and controlled to within one percent Of the desired .=onrpntr>tinn l m . , a l t h = t CC-.. .-.e-- - - * - _ -

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FAILURE MODE

- Poor tool life

-Rust

.Size variation

POTENTIAL CAUSE

-Improper concentration

-Inadequate flow

CONTROL

-Correct concentration

-Determine correct flow -Install flow meter

-Dirty fluid

-Temperature is excessive

-Incorrect concentrat ion

-Additive depletion -Contamination

-Improper bracti'ces

-Inadequate tool

-Incorrect

-Temperature swings

-High dirt level

life

concentration

-Incorrect flo'w

-Improve filtration -Eliminate contaminatior

-Change fluid chemistry

-Increase fluid flow -Reduce coolant

-Reduce cutting speeds

-Correct concentration

-Moni tor and control -Determine source and

-Determine problem and

temper a tur e

manage

correct

- See above - Correct concentration - Maintain constant - Improve filtration - Change coolant - Correct flow - Install flow meter

coo rant temperature

chemistry

And the list goes on for whatever problem is critical to your operation.

Addressing all of the potential areas is a difficult task. You have to step back. take a fresh l o o k at your process, and ask yourself new questions. For example, to determine i f you have a . . . . - =4.">A., _*_._ __-A:..-- ~

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FLUID NANAGENENT PLAN - EXAMPLE 1

PROBLEM STATEMENT: Fluids and related systems are not in a steady state of control causing the process to operate in a wasteful and inefficient manner with numerous fluid related problems . OBJECTIVE: Obtain steady state condition.

Action: Obtain concentration control. - Determine reliable concentration measurement method - Determine desired concentration -range - Determine individual responsible for fluid or - Train individual responsible for fluid or system. - Determine equipment necessary to maintain accurate - Establish documentation procedures - Establish audit procedures to assure compliance

system

control

on: Reduce contamination o f fluid. - Identify contaminates - Develop procedures to eliminate or reduce - Develop procedures to monitor those that can not be contaminants

eliminated

on: Eliminate special causes. - Identify and manage other factors such as different operators, different operating procedures, outside influences, or anything that causes disruptions to a steady state condition.

Once a steady state of condition is obtained a plan can be developed that will move a process beyond Status-quo. Now is when real process improvements will be seen. A plan to do this might begin as follows:

FLUID MANAGEMENT PLAN - EXAMPLE 2 PROBLEM STATEMENT: The size variation of class two parts is above acceptable levels.

OBJECTIVE: Reduce size variation due to fluid temperature influences.

ACTION: - Determine actual temperature changes - Determine actual size variation - Determine mean optimum operating temperature and - Specify, purchase, install temperature control

range

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coolant life to more reasonable levels. With a few more checks such as dirt level, incoming water quality, additive depletion levels, and make up rates they were able to extend system life indefinitely. They now have a stable coolant system, and production improvements continue to be seen.

Organization of resaurces - A s the analysis of the plant is taking place, attention needs to be placed on who currently is and who should be involved in the management of fluids in the plant. These resources need to be organized with a focus on fluid management.

Fluids are in almost every department within a plant. Determining who is actually in charge of a system or fluid is difficult enough. Most fluids have an interaction with fluids from both the previous department and the next department. Then they end up in waste treat. Who is in charge? Most plants have a lab, either in house or outside doing the monitoring. What stake do they have in the fluid or system? What about the contaminants entering the fluid? Are they under the same control as the person controlling the fluid? Is the fluid manufacturer controlling the fluid? The fluid salesman?

In most cases there is no one truly i n charge. If any one is said to be in charge it is the actual technician doing'the work. If so, let us hope he is not among the lowest paid in the plant. Let us hope he has had extensive training in fluid management, project management, people management, liability law, chemistry, filtration equipment, waste treat, EPR requirements, and OSHA requirements to name a few of the necessary skills.

You can see from this list of what i5 required to properly manage plant fluids that several resources should be responsible for fluid management. It most certainly needs to be individuals who have a stake in the outcome. Hopefully, a project champion, someone with a strong interest in fluids, will be available as a team leader. The most successful fluid management program will consist of a team that covers all of the needed resources and covers all departments that have a stake in the outtome.

Development o f a management plan - Once the initial analysis work has been accomplished and the necessary manpower organized, a fluid management plan can be developed. Initially, actions to correct the obvious such as stopping leaks, providing Concentration control methods. fining filtration equipment, and providing documentation of your current status should be accomplished. These are basic housekeeping type chores that must be accomplished in order to begin to understand the problems. Next, a COntrOlled steady state condition must be achieved as well as the elimination of wasteful Practices and reduced waste treat efforts. For a plant that is in overall reasonable control this stage will be fairly simple to complete. The following plan provides a format that can be used to chtain a steady state condition for a Single machine's fluid, a department, or an entire plant. This plan might begin as f o 1 lows:

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MRR89-455-9

actually were reduced once the fluid was under control. Generally, fluid systems that are under control are far more economical than systems out of control and cost savings extend beyond the cost of the fluids.

Lab equipment - For any parameter that needs monitored, the apparatus to do the job must be available. for many fluids and systems all that is needed is a refractometer or a titration kit. For others more elaborate equipment will be needed. The important issue is that you should be able to test for every parameter that is important to your process. Below is a chart with some of these parameters for various fluids. It is necessary to have all the instrumentation t,o monitor each parameter.

F'-U I D

Coo 1 ants

Cleaners

Plating solutions

Hydr au 1 i c and Lubricating oils

Rust inhibitor (water base)

Incoming water

PARAMETER TO MONITOR

Concentrat ion Rust protection Dirt level Bacteria level Tramp o i l

Concentrat ion Temper a tur e Rust protection Dirt level

Concen tr a t ion Dissolved solids Temper a tur e

viscosity acid number Ua t er Particle count

Concentration Rust protection

Hardness Chlorine level

Control systems - The obvious goal for each fluid is to know continuously the condition o f all the parameters that are critical to your operation. Each tank must have some type of control. On individual tanks this may be left up to the operator f o r water and Concentration additions. However, concentration checks must be made and recorded regularly. On main systems this control will have to be automatic ulth much more elaborate monitoring and control. The best system for adding makeup Water and concentrate

mag-455-8 I system

parameters - Document performance and fine tune operating

QEJECTIVE: Reduce size variation due to fluid influenced tool wear.

ACTION: - Obtain accurate current data on all variables ., a

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assumed to effect tool life

flow rate, etc. - concentration, dirt level, tramp oil, contaminationr

- Obtain current tool life data - Develop and conduct controlled test of each variable - Develop method to maintain optimum condition individually

determined in above tests

You can now begin to understand that the implementation of these plans would only be possible if you know what condition the fluid is in and if it is remaining in a steady state condition.

IMPLEMENTATION OF THE MCINCIGEMENT PLAN

Once you have organized your direction of what to accomplish, there are some tools to use that will help guarantee your success. The tools for fluid management can be broken into the following components. Each of these areas will need to be addressed for effective fluid management.

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- Technical support Tor each system under consideration - Lab equipment - Controlled fluid makeup - Monitoring of fluids and systems - Documentation of fluids, systems, and the effects on the - Contamination to the system - Strong vender support - Top quality fluids - An education program

process

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I Each of these items will now,be discussed:

Technical support - You must have the people with the technical ability and the time to monitor, evaluate. and control the fluids. This workload will usually be much heavier initially until tests are developed, systems and fluids are understood, and controls are in place. Once everything is in order the manpower will probably be reduced to below your current levels because systems in control are easier to control. The eyelet press Operation mentioned earlier solved their excessive tooling costs by the addition of a fluid technician who was resoonsibla for monitoring and maintaining coolants. The labor costs for maintaining the department's fluid

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for everything that is critical to your process, somehow i t must be monitored. When a standard test is not available, a test must be developed that allows monitoring of that condition.

The development of these tests is shown by a problem that developed in a grind coolant system. In one particular system the coolant supplier was conducting a weekly test and showing an average dirt level of 70ppm. What did this tell us? Whenever a question came up as to the cause of a particular problem we had no data until a week later and then it was only a snapshot. What was needed was to be able to continuously monitor the dirt level until it was understood. We developed a simple settling test that allows us to know in a few hours exactly the relative dirt level.. Over time we learned the exact nature of the dirt level in the systems, and now use it as a tool to improve the process.

Another example of the importance of these monitoring tests can be shown by the classic problem o f in process rust. It normally never is quite determined what caused the rust to occur before the problem goes away and reappears somewhere else. If a thorough investigation is carried out, the season changes, and again an understanding of the problem goes by the wayside.

Suppose a plant is conducting a regular rust preventative test o f all of the critical fluids in use and a regular audit of actual rust protection of in process work? Now any process type problem. would show up consistently and could be resolved permanently. Plny other rust problem would not be related to a process problem, and a specific cause is easily identified. The vicious circle is broken, and true improvements may be made.

A plant was experiencing this particular type of a problem that was resolved with the development o f three different rust test. The evolution of these tests is interesting because i f shows that when a parameter is critical a test can be developed that will monitor the condition of that parameter.

The problem originated with a Coolant that was believed to be causing rust from time to time in a particular department. Of course the coolant supplier claimed that the coolant had an excellent rust inhibitor package. Yetr the rust would continue on a sporadic ba5is. 13 simple drop test on cast iron was developed (similar to the standard cast iron chip test) so that several products could be run side by side easily. With this test the problem was isolated to incoming drums that had no rust inhibitor. I t was later realized that about one in four drums had inadequate rust inhibitor.

Another rust problem was from a dryer in the same department. Again, the rust problem never occurred consistently enough to really identify the problem. What was needed was a method to evaluate t h e actual rust protection on a dry part. What was developed i s what is called the freezer rust test. With thls test w e were a b l e to take any part anywhere in the process and determlne

MF.89-455-10

is one that makes the additions in a continuous manner. This typically consists of a flow meter set to add water on a 24 hour per day basis. For example, if a tank needs 240 gallons of makeup water per day the flow meter would be Set for 10 gallons per hour. The concentrate would be added with a metering pump set for whatever was necessary to maintain concentration level. Systems of this type are capable of maintaining fluid levels quite accurately and concentration to within one half percent. In addition, by placing the discharge of the metered concentrate into the metered makeup water line which discharges into the suction of a filter pump you can maximize the coolant mining. It also avoids the potential of shocking the system with a temperature change.

OPTIMUM COOLANT MAKEUP METHOD

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Monitoring -There is still one area that causes fluid management plans to fail. Exactly how do you monitor a fluid to know what condition it is in and what effect i t is having o n your process? If you leave it up to the supplier you are at quite a disadvantage because they are removed from your operation. The tests are primarily for their benefit (to keep the fluid from going rancid), and the tests have such a time delay factor that they frequently are o f little use to you. They can be used as a monitor of how well the plant’s monitoring is performing, but they are not for actual system control.

This means that you must run your own test and monitoring programs in house. The only way improvements can be obtained and maintained is to know at any given time the condition o f the fluid. If tool life is related to concentration, then the Concentration must be tested and maintained at the necessary level. If finish is related to the amount of fines in a fluid, then the actual level must be know at any given time. The same is true for rust protection. If incoming water quality changes from time to time and i t is known to affect cleanibility. rust protection, sump life, or whatever, then its condition must be tracked and recorded. So

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COOLANT CONCENTRATION CHECK

TANK CAPACITY--------

DATE I RECHARGED I READING I READING I WATER I CONCEN. I READINGS I BY

Coolants should be inspected daily. RefractQmeter readings should be taken daily and whenever an addition Of water or coolant is made. Contaminated tanks should be drained. thoroughly washed, and recharged with fresh solution at the proper Concentration. Always add Concentration to water. never water to concentrate. The better the tank is cleaned, and the cleaner the maCnlne is kept, the better the coolant wall perform and the longer it will last.

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the relative rust protection o n that part. A part; is taken from the process, dried, placed in a freezer until a specific temperature is reached, and then placed in a beaker suspended above distilled water. Two hours later the part is examined. This has proven to be one of the most valuable tests for monitoring rust protection. It is responsive enough that a 1% variation from operating concentration will show a marked difference in rust . protection. With this test Quality Control is able to set up an audit procedure which resolved the rust problem and guarantees rust protection.

Another simple test now used to monitor how the coolant is protecting the machine itself is simply placing a small ground cast iron slab into a beaker o f the used coolant. With this test monitoring of the machine can be done with reliable results.

This same scenario applies to all the other parameters that are important to an operation. Most tests are straight forward. Some of them may take time to develop. If a parameter is important to your process a test will be well worth the development. In all likelihood, as the test is being developed more valuable information will be obtained. This in turn will drive the process toward improvements and will create additional support from those that use the fluid. It will also drive your supplier to perform at their maximum capacity which.he1ps you in controlling your fluid or system.

Documentation - Once work begins o n trying to get a fluid under control, documentation needs to be done. The only way to hold the gains is to record where you were and where you are. Often there is a multivariable interaction occurring that the effects of a change whether it be concentration, dirt level, foam, or whatever will only show up over time. For a main coolant system a chart frequently used is:

MAIN COOLANT SYSTEM DAILY LOG

D.0 DIRT DATE pH CONCENTRATION DROP LEVEL RUST COMMENTS

MAIN COOLANT SYSTEM DAILY LOG

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For a department made up of individual machine sumps a chart frequently used is as follows:

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used in a washer cost $1.75 per gallon. The concentration was maintained at 6% for a total charge cost of 552.50. This washer had to be dumped and recharged daily at a yearly cost of 812,600 for chemicals alone. Changing to a 13.50 per gallon product extended the cleaner to a once a week dump and recharge reducing the chemical costs alone by about t10.000 per year. This was with an actual improvement in part quality and much reduced operator attention.

Education - Education of everyone involved with a fluid is an area that also yields solid improvements. An operator understanding the fluids in use is as important as the operator understanding his machine. We would not think of asking an operator to operate a machine without proper training. but how much training is provided on the fluid used? Is the fluid important to obtaining the quality and productivity we are after? The more an operator knows'about his machine the better he performs. The more his knowledge of how the fluid interacts the better he can perform also. Education of those involved with fluids is also the best way to avoid problems with the safety and health aspects of fluids. 6 typical training program should cover the following topics:

Difference between oils, water solubles, semi-synthetics, and synthetics Concentration control importance Concentration control methods Importance of documentation Mixing procedures pH what it means, how i t works , Importance of keeping fluids clean methods of keeping fluids clean, oil skimmers, sump cleaning machines, filtration equipment Examples of what fluids look like and what various contaminants do to them How different concentrations affect: rust, surface finish, tool wear, product life, etc What rust is, what causes it, and how to prevent it How dirt level effects fluid performance Factors to be concerned with in fluid selection Ways to reduce dermatitis Waste treatment aspects of .fluids Usage reducing practices Health and safety issues OSHA requirements

Co nc 1 us i on

The dependence of our manufacturing processes on the fluid condition makes the management of our fluids extremely vital. If we are going to be able to control and predict our process, we must be able to control and predict the fluid condition at all times. Once we obtain this control we can move our production process in the direction of greater productivity and reduced Costs while obtaining the benefits o f a well managed system.

MR89-455-14

Documentation of your process variables must also be kept with your system data. After careful analysis of all the data to date, if there is any correlation between a process shift and a fluid condition change, it will become evident. Some of the largest gains in quality and productivity are obtained this way.

This documentation also yields another benefit. If you have a water leak, an unusual amount of contaminates, depleting of a rust inhibitor, or anything out of the ordinary, it becomes apparent sooner with documentation. Corrective action can take place before the process is effected.

Contamination - Another aggravation to maintaining control of a system is contamination to a system. Any contamination that can be eliminated needs to be done. The importance of this cannot be over stated. In one system that was having a recurrence of a bacteria problem, the problem was traced to a solvent/oil based rust inhibitor into which parts were being dipped between operations. Switching to a water base rust inhibitor eliminated the contamination to the system and actually contributed to the coolants rust inhibitor package. An additional benefit was a reduction in dermatitis on operators working with water base fluids next to solvent/oil base fluids.

Strong vender support - Since an outside vender designed and manufactured the fluid in use they must be a partner in its operation. Typically, the more you know and understand about your' fluid and its.performance, the greater the support you are able to obtain from the vender. One o f the on-going objectives for the plant should always be to obtain all of the technical support available from a vender. In the situation mentioned earlier involving the tuo 12,000 gallon coolant systems, there was initially no vender support. The system was being maintained so poorly that all the vender could do was sell them the product for each dump and recharge. as the department became more sophisticated at monitoring and controlling the system, they obtained a steady state condition of the fluid. They then were able to start working with the coolant supplier to optimize their fluid. Now they are obtaining fantastic supplier support and are watching fluid costs continue downward while fluid influenced performance continues upward. For example, a recent occurrence of rust o n the inside of some machines was being blamed on the coolant. It appeared to be critical enough to require a complete dump and recharge of both systems - a S10,OOO expense. But through quick technical support from the coolant supplier and in house testing the problem was traced to one maintenance procedure that had been changed without anyones' knowledge. Had the system not been under control and the coolant supplier not known that the plant had the system under good control the dump and recharge would have been ordered.

d

High Quality Fluids - 6 better quality fluid to begin wi~th will obviously be simpler to control. In case after case the better the fluid the lower the overall cost. In one case a cleaner that was

METALWORK1 NG FLU I D S

-a 31 mi a

MARCH 12-14,1991 DEARBORN INN HOTEL

DEARBORN (DETROIT), MICHIGAN

VOLUME 1

Society of Manufacturing Engineers 0