Metalworking Fluid Selection Checklist: Application Survey

What is a metalworking fluid application survey for, and when do you use it?

A metalworking fluid application survey is a fill-in form that records the plant conditions a new fluid has to work in, so that a fluid choice rests on the process and not on habit. A supplier's technical service engineer uses it to prepare a first visit, a plant engineer uses it before asking suppliers for a proposal, and either can use it again when a machine, a metal or the water source changes.

The trade guidance behind the form is direct about the reason. STLE's TLT best practices column says that selection "should be based upon the process requirements and potential benefits from the fluid choice rather than a match for the same type of product that was always used in the past" (STLE TLT, 2009). ASTM E1497-23 is a standard practice that sets out guidelines for the selection and safe use of metal removal fluids, including product selection, storage, dispensing and maintenance (ASTM E1497-23). The US OSHA manual points to the NCMS Metalworking Fluids Optimization Guide for the factors to consider when selecting metal removal fluids (OSHA Metalworking Fluids manual).

Use the survey before any product name enters the discussion. Fill the blank form at the visit, attach the plant records it asks for, and mark each answer as a must-have, which rules a fluid out, or a preference, which only ranks the fluids that remain. The editable Word survey is at the end of this page.

Which sections does the metalworking fluid application survey have?

The metalworking fluid application survey has eight sections in a fixed order plus an open-items list, from the machines and sump to the success criteria, and each field carries its unit so that a later visit can compare like with like. The form header records the request type: first selection, replacement or re-check after a change. The table below previews every section and decides which answers are must-haves that rule a fluid out; example values are illustrative.

Fields left blank stay on the form as open items, so the next reader sees what was not asked. The key row is section 6: a restriction recorded with the role that stated it and the reason is a must-have that removes a candidate fluid, while a restriction with no stated reason goes back to the customer as an open question.

Which machine, sump and operation details does a metalworking fluid survey need?

A metalworking fluid survey needs the machine and sump layout, the chip and oil load, the dilution method and the severity of each operation, because these decide how much maintenance a fluid gets and how hard it has to work. STLE's selection checklist asks whether machines have individual fluid reservoirs or a central system, noting that fluids in individual machines "need to be able to run without much maintenance or attention" (STLE TLT, 2009).

The same checklist asks whether machines have a system for removing chips, whether they are new and well sealed or older and leak oil, and how a candidate fluid handles leak oil, by rejecting it or emulsifying it (STLE TLT, 2009). It also asks how the fluid is diluted: by a premix tank, an automatic proportioning device, or by adding concentrate and water directly to the sump (STLE TLT, 2009). Record sump volume in liters, since it feeds the later usage comparison.

Operation severity sets the lubricity class. STLE describes boundary lubricants for light to moderate duty and extreme pressure additives, which react with metal surfaces under high heat or pressure, for heavy-duty work, and warns that a heavy-duty product in a light-duty operation "may offer no measurable improvement over a lighter duty fluid" (STLE TLT, 2009). List each operation with its alloy.

Record operator contact as well. STLE notes that skin contact time is probably high at individual machines, requiring a very mild fluid, and minimal on automated transfer lines (STLE TLT, 2009).

Which water quality values decide a water-miscible metalworking fluid?

Mix water hardness, chloride, sulfate and the water source decide a water-miscible metalworking fluid, because water makes up most of the in-use fluid and keeps being added. STLE puts water at typically 90% to 95% of the in-use fluid, constantly added to replace evaporation losses (STLE TLT, 2009). Water that is too hard leads to instability of the diluted mix and corrosion problems, and water that is too soft may cause foaming (STLE TLT, 2009).

The OSHA manual explains the chemistry behind each value. Calcium and magnesium make water hard; they form scale on evaporation and insoluble soap scum with many fluids. Sulfates promote sulfate-reducing bacteria that produce a "rotten egg" odor, and sulfates and chlorides are corrosive to metal and contribute to rust (OSHA Metalworking Fluids manual). STLE adds that softened water is not as good as deionized or reverse osmosis water for corrosion control and emulsion stability (STLE TLT, 2009).

The survey records the plant value; the limit comes from the fluid maker. UK guidance tells users to check input water quality for hardness, pH and bacteria and to consult the fluid supplier about suitable water quality requirements (HSE MW5, 2021). Write hardness in mg/L as CaCO3, chloride and sulfate in mg/L, and name the laboratory and sample date. An analysis older than the last change of source or treatment does not describe the water now in use. If the plant cannot treat the water, mark tolerance of it as a must-have.

How do you record the current fluid's performance in the survey?

Record the current metalworking fluid's performance as measured values with dates: target and measured concentration in percent, change interval in months, top-up volume per week, tool life and each problem seen. These values become the baseline a replacement has to match, so mark a value from memory as reported rather than measured.

Concentration needs both numbers. The OSHA manual says that a system run at low concentration may see decreased tool life, bacteria or fungus problems and corrosion, and one run too high may see dermatitis, foaming and heavy residues (OSHA Metalworking Fluids manual). A gap between the target and the measured value often explains a complaint before the fluid itself is blamed, so write the measuring method and the refractometer factor next to the reading.

Problems go in with their date and machine. STLE's checklist asks directly whether there are problems with the fluid currently in use and what contaminants are expected to enter the system (STLE TLT, 2009). Odor, foam, residue, rust on parts or machines and skin complaints each get a line, with how often they occur.

Attach the plant's own records rather than retyping them. UK guidance says to keep records of all fluid quality tests for at least five years, in a table or graph that makes trends easy to spot (HSE MW5, 2021). A concentration and pH log shows whether a problem is constant or follows a season, a shift or a change of water.

Which health, ingredient and disposal limits rule a metalworking fluid out?

Ingredient bans, exposure limits and the plant's waste route rule a metalworking fluid out when they are written into law, a permit or the customer's own rules, so the survey records each one with its source. The OSHA manual advises avoiding potentially carcinogenic components such as oils containing PAHs, chlorinated paraffins, alkanolamines, nitrites and formaldehyde release biocides, and says nitrite-containing materials should not be added to fluids containing ethanolamines (OSHA Metalworking Fluids manual).

In Germany, water-miscible coolants may not contain nitrosating agents or their precursors (TRGS 611, 2007, section 4.1), may not contain secondary amines as components, and secondary amines from impurities may not exceed 0.2% by mass of the concentrate (TRGS 611, 2007, section 4.2). In the US, the OSHA PELs that apply are 5 mg/m3 (8-hour TWA) for mineral oil mist and 15 mg/m3 (8-hour TWA) for particulates not otherwise classified, while NIOSH recommends 0.4 mg/m3 thoracic particulate for metalworking fluid aerosols as a TWA for up to 10 hours a day in a 40-hour week (OSHA Metalworking Fluids manual).

The OSHA manual says to follow the manufacturer's instructions and government regulations for disposal, and that local treatment works are likely to have their own discharge regulations (OSHA Metalworking Fluids manual). STLE asks what method is used for fluid disposal and advises testing the fluid with that method (STLE TLT, 2009). Record the route and the permit limits; handling steps come from each product's SDS.

STLE warns against selecting from "someone else's list of forbidden chemicals" without knowing why each material is forbidden (STLE TLT, 2009).

How do you turn survey answers into must-have requirements and success criteria?

Turn survey answers into must-have requirements by asking, for each answer, whether a fluid that fails it would be rejected outright; if yes it is a must-have, and if it would only lose points it is a preference. A ban written into a permit or regulation, a metal on the machine that the fluid must not stain, and a water quality the plant cannot change are typical must-haves. Lower odor or a longer change interval are typical preferences, unless the customer states a limit.

Record who stated each requirement and the function it protects. Purchasing, quality, operations and maintenance often state different limits for the same item, and the survey keeps both values with their roles rather than averaging them. A requirement whose reason is unknown stays as an open item with the person who can answer it.

Each success criterion needs a threshold, a unit, a method and a judge. Tool life can be stated as parts per edge against the current fluid on the same operation; ferrous corrosion control can be screened with ASTM D4627-22, the iron chip corrosion test for water-miscible metalworking fluids (ASTM D4627-22). ASTM notes that conditions and metals found in practice "will not correlate quantitatively" with that test (ASTM D4627-22), and STLE advises that laboratory screening tests relate to the actual operation (STLE TLT, 2009). A criterion with no method or no threshold is written down as not yet decidable, so that no one judges a trial against it later.

Metalworking fluid survey filled in (illustrative)

A filled metalworking fluid survey for one cell of six machining centers shows how answers become must-haves, preferences and success criteria. Every machine, value, role and limit in this example is illustrative and comes from no real plant. The table below decides which answers remove a candidate fluid in this example (illustrative).

The key row is the boron ban: because the wastewater operator stated it and the permit is attached, it removes every candidate that contains boron before any comparison of performance (illustrative). The same answers also tell suppliers what not to propose, which shortens the list before any trial is planned. Open items in this example are the measured concentration on two machines and the permit's oil limit, each with the name of the person who will supply it.

Where the metalworking fluid survey does not fit

The metalworking fluid survey does not fit a fluid that is already failing, an exposure assessment or a legal compliance check. It records the conditions a new fluid must meet; it does not find the cause of a problem in the current system, and a sump with odor, rust or dermatitis complaints needs a troubleshooting record of its own before a replacement is chosen.

Straight oils use only part of the form. ASTM E1497-23 notes that straight oils are not intended to be diluted with water before use (ASTM E1497-23), so the mix water section and the concentration fields do not apply. ISO 6743-7:1986, confirmed in 2026, classifies metalworking lubricants as family M (ISO 6743-7:1986), and a plant that already specifies fluids by such a category can record it in section 5, but a category says little about performance: STLE notes that the synthetic, semisynthetic and soluble oil classes only indicate oil content (STLE TLT, 2009).

The survey is not a substitute for air sampling or a risk assessment. Exposure limits recorded in section 6 describe the rules that apply; whether a plant meets them needs measurement. Regulations differ by country and by local permit, so check the rules for the site before removing a field. Finally, the survey carries no supplier-specific limits: hardness or chloride limits for a candidate fluid come from that fluid's technical data sheet and are compared with the plant values afterwards.

Metalworking fluid selection checklist

A metalworking fluid selection checklist confirms, before the survey is sent to suppliers or filed, that each answer can rule a fluid in or out.

• Each machine has its type, sump volume in L, chip removal and filtration recorded.

• The dilution method is named: premix tank, proportioner or direct addition.

• Every operation has its alloy and a severity of light, moderate or heavy.

• Machine component metals, such as aluminum or copper parts, are listed.

• Operator skin contact time is recorded per machine type.

• Mix water hardness, chloride, sulfate and pH have units, a laboratory and a sample date.

• The water source and any treatment are named.

• Current fluid concentration shows the target, the measured value and the method.

• Change interval, weekly top-up and problems with dates are recorded.

• Each restriction names who stated it and why.

• The disposal route is named and any permit limits are attached.

• Every answer is tagged must-have or preference.

• Every success criterion has a threshold, a unit, a method and a judge.

• Open items name the person who will answer them.

Lubinpla's product recommendation task confirms the requirements and success criteria from your own records before it compares any candidate, and a filled survey saved as PDF or a photo can go into the work log through bulk upload, which takes txt, md, csv, pdf and image files.