Comprehensive industry standards for many industrial lubricants and fluids are notably lacking. Such standards would be of great benefit to end users in reducing the time and expense associated with evaluating potential products. Product management is becoming more important for worker health and process productivity, and standards or guidance in this area are important.

This article discusses progress on development of fluid and lubricant standards. To protect worker health, GM developed standards more than decade ago to ensure the use of only highly refined base oils, and has largely implemented them. Performance standards pose a somewhat greater challenge. GM now has well defined standards for hydraulic fluids, gear oils, etc., while standards for metal removal fluids are currently under development. Quality control parameter checks have been systematized and implemented within GM. Plants now have references with which to check products delivered. The current state of GM standards will be reviewed. A systematized effort to improve and standardize lubricant and fluid management is also critical, and will be covered briefly. 

When I became involved in industrial lubricants, there were some standards available, although many were company standards and not true consensus standards. In General Motors, there was a Fisher Body Materials specification that was over ten years old, seldom used and probably inadequate. For maintenance lubricants (hydraulic fluids, gear lubricants, way oils, spindle oils, greases and so on), there were a lot of good test methods available, American Society for Testing and Materials (ASTM) International Standards Organization (ISO) and others. Also, since on the industrial side GM is actually the direct customer, we could write our own standards.

The situation was more difficult for metal removal fluids (MRFs). We really didn’t find any suitable industry standards or anything internally. To complicate matters, there were only a handful of consensus test methods available, and many parameters were more or less completely undefined. On a corporate basis, we had far too many different MRFs and tended to purchase MRFs as specialized products rather than commodities. Our expectations were based on company reputation, price or gut feel – not hard data. We did not have systematic checks of key quality control parameters (e.g., sulfur, chlorine, base number, fat content). When tool life suddenly dropped in a given system, there was no easy way to begin to eliminate a change in MRF formulation as a possible cause. GM plants sometimes experienced periodic health and safety issues, such as dermatitis and respiratory complaints.

Standards Development

We embarked on the task of developing standards, with the “we” being the GM LS2 committee. This group, at the time of this article more than 150 in number, is composed of anyone involved in plant lubrication or fluid management issues. LS2 is composed of plant and central staff people, oilers, maintenance managers, capacity assurance coordinators, machine operators, environmental engineers, etc. Some are salaried; most are hourly. All share a desire to do a better job on lubricant and fluid issues within GM. While no one LS2 member has all of the knowledge, collectively they are a tremendous resource and the reason why GM has made considerable progress on lubrication issues. It is worth noting that our chemical managers and suppliers also participate in LS2 meetings and add considerable value.

To write specifications, we first defined key parameters, sought relevant test methods, selected the most promising methods, inserted placeholders for parameters for which no standard tests appeared to exist, and established pass/fail limits, where possible. Requesting “report” on those parameters without a specified limit helped us generate a database with which to establish future limits. We must continuously seek plant experience and attempt to correlate this with the specifications, semi-quantitatively or at least qualitatively. We then continuously iterate all steps, from rechecking the parameters (are there new demands or constraints?) to tweaking test methods, developing new test methods and setting and revising limits.

Worker Health

The first priority in setting specifications is protecting the health of our workers. Rather than specifying refinery processing conditions as the International Agency for Research on Cancer (IARC) had, it was more important and more reasonable to specify the quality of the finished base oils used in industrial lubricants. GM developed and released a base oil specification in 1994. Since 1997, GM has required that any mineral oil components of lubricants and fluids must meet these base oil specifications for metals, polynuclear aromatic compounds, PCBs, halogens and Mutagenicity. We have and continue to verify that virtually all maintenance lubricants and MRFs in GM plants meet them.

Performance Specifications

Next was the task of developing performance specifications. LS2 clearly recognized that maintenance lubricants and MRFs must be approached differently. For maintenance lubricants (a hydraulic fluid, for instance), the specification’s intent is to exclude all unsatisfactory fluids and address virtually all quantifiable performance requirements. A hydraulic fluid meeting the LS2 performance requirements, if maintained properly, should provide satisfactory performance in 99% of its intended applications. MRFs, however, are just too complex to write complete, hard specifications in any reasonable time period. The philosophy for metal removal fluids had to be different than that for maintenance lubricants; we must accept less than perfection. The intent of the specification is to improve our odds of finding an acceptable fluid. We may inadvertently exclude some good fluids, but with continuous iteration, should reduce the number of inappropriate or poorer performing fluids.

The performance specifications first include key physical properties, such as viscosity, flash point, etc. Performance tests make up the bulk of the standard, and include properties such as wear protection, oxidation stability, thermal stability, foaming tendency, corrosion protection, effects on seals, etc. For the commonly used lubricants, the standards are very comprehensive and pretty rigorous. There is actually an LS2 approval process and a fairly voluminous list of products approved. This will be discussed in more detail in the later section on quality control. For metal removal fluids, things are not as far along. We have identified several key properties that we wanted to include in the specifications, as shown in Tables 1 and 2 for straight and aqueous metal removal fluids, respectively. For some parameters, we have tests and clearly defined limits. For others, we have a test, but no limits. For still others, we really only have a “placeholder” to indicate that the property is important, but that we do not yet know how to define it.

Test and Passing Limit

Test But No Limit

No Test, Placeholder Only

Iron rusting

Physical properties

Misting tendency

Copper corrosion

Foaming tendency

Machining properties

Aluminum corrosion

Frictional properties

Waste treatability

Extreme pressure properties

Oxidation stability

 

Seal compatibility

Wear properties

 

 

Thermal stability

 

 

Filterability

 

Table 1. Key Properties of Straight Metal Removal Fluids.

Test and Passing Limit

Test but No Limit

No Test, Placeholder Only

Same as for straight oils

Same as for straight oils

Same as for straight oils

 

Emulsion stability

 

 

Sticking/gumming tendency

 

 

Bioresistance

 

 

Tramp Oil Rejection

 

 

Waste Treatability

 

Table 2. Key Properties of Aqueous Metal Removal Fluids.

The specifications have evolved and will continue to do so.

Quality Control

So LS2 are well on the way to defining what we believe will be better lubricants. But how do we know what is being delivered to our plants is the fluid or lubricant that was shown to pass all of the LS2 requirements? To address quality control issues, each individual standard in LS2 has a “boilerplate section.” This section requires that the supplier be ISO or QS 9000 certified, that products must be submitted for approval (LS2 does not allow suppliers to self certify) and that no changes to an approved product are allowed without requesting re-approval. The approval process requires complete “recipe” disclosure, test data for all parameters and test reports for the most critical parameters.

For maintenance lubricants, the LS2 committee has a monitoring program. The first year’s program sampled 20 different LS2-approved lubricants at point of delivery to the plants. Viscosity, metals, water, particle count and some base oil properties were checked against the expected “fingerprint” provided in the original approval request data. Of the 20 products, three suppliers initiated changes to their quality assurance procedures or changed their raw material suppliers as a result of discovered non-compliance. LS2 revoked the approvals of one other supplier due to an apparent willful disregard for the provisions prohibiting changes to approved products. With respect to MRFs, LS2 set out to establish key physical and chemical parameters (actually blending targets) that we expect to remain reasonably consistent from MRF batch to batch. But even this was not trivial, as the methods took some sorting out so that everyone measuring the same property of the same fluid would get the same result within some reasonable reproducibility. We were able to accomplish this by a task group of plant people and suppliers.

Lubricant and Fluid Management

Complete lubricant management is probably outside the scope of any specification, but LS2 at least tries to help. There are LS2 sections on storage and handling, oil analysis, recycling and oil management, that provide guidance to the plants. Existing Quality Network initiatives in GM work hand in hand to help with proper maintenance of equipment and lubricants.

With respect to metal removal fluid management, GM’s Powertrain Division established a template for the elements required for properly managing MRFs. Each plant needs to develop a plan that includes the following elements:

  • Design of MRF management responsibilities, including identifying the person or team with responsibility for the program.

  • Written testing protocols, where each system will have a specific protocol developed to identify sampling frequency, sampling collection, handling, and results tracking.

  • Data collection and tracking that encourage the use of an access database system.

  • MRF system monitoring, maintenance, contamination control and cleaning.

  • MRF exposure reduction plan.

We incorporated this template into the LS2 standard and are currently reviewing our plant plans, from which to develop a set of best practice targets. Training is also important, particularly for our on-site chemical managers.

It is critical for an end-user to define the properties of the fluids and lubricants used in their plants, to routinely check that the proper product is being delivered and to carefully and consistently maintain it. These are all interrelated, and are critical to protecting worker health and safety, providing quality parts, optimizing equipment life and minimizing undesirable environmental effects.

Editors Note: This article is based on the paper originally presented at the Lubrication Excellence 2005 Conference and Exhibition.

References

  • ASTM Annual Book of Standards, Vols. 5.01, 5.02, 5.03, 5.04, American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA, 19428-2959.
  • General Motors Maintenance Lubricant Standard LS2 for Industrial Equipment and Machine Tools, Document No. GM 1721, Version 5, November 30, 2004.
  • IARC, Mineral Oils: untreated and mildly treated oils (Group 1). Highly refined oils (Group 3). In IARC monographs on the evaluation of carcinogenic risks to humans. Overall evaluation of carcinogenicity: An updating of IARC monographs. Vols. 1-42, Suppl. 7. Lyon, France, International Agency for Research on Cancer, pp 67-68, 1987.
  • ISO, International Organization for Standardization, Geneva, Switzerland.