Machine Lubrication and Cutting Fluids

Machine Lubrication and Cutting Fluids

Chemical Cutting Fluids

• Non-toxic and non-hazardous
• Biodegradable
• Does not contain sulfur, chlorinated solvents, chlorine, water, mineral oil, or inactive fillers
• Effective on tough-to-drill metals and alloys like beryllium, molybdenum, stainless steel, and Stellite
• Great for cutting, drilling, tapping, or threading metal components
• Ozone-Friendly formula contains no 1,1,1 trichloroethane

Soluble Oils

• Emulsify into water and contain 60-85% mineral oil
• Least expensive fluid alternative
• Offer good lubrication and have a great cooling capacity
• Emulsions produce a milky white product when mixed with water

Semi-Synthetic Fluids

• Emulsify into water and comprise 5-50% mineral oil
• Heat transfer performance and cost lie between synthetic and soluble fluids

Full Synthetic Fluids

• Provide the best cooling performance and microbial control
• Clear liquid increases visibility
• Elevated corrosion control

Delivery Systems

• Compressed air delivery: used for chip evacuation but does not take away heat effectively
• MQL (minimum quantity lubrication) Misting: compressed air with a minimum quantity of oil for lubrication
• Cryogenic coolant: a liquefied gas used as a coolant to maximize the cooling effect

Flood Application

• Apply coolant directly on the tool for all machining operations

Thru-Spindle Cutting Fluid Application

• Good for cooling at deep machining conditions
• Excellent chip evacuation

Thru-Spindle Misting System

• Air infused with coolants
• Good chip evacuation
• Excellent cooling levels
• Ease of viewing

Misting Application

• Less potential for contamination in tanks
• Ease of sight line
• High efficiency cooling effect
• Good chip evacuation

Purpose of Lubrication

• Supports a reduction of machine tool wear
• Reduces friction
• Supports corrosion resistance
• Lubricant supports machine tool seal health
• Cleaning, cooling, and prevents adhesion

Types of Friction

• Sliding friction: occurs as two different objects slide over each other
• Rolling friction: occurs as two round objects roll around or on top of each other
• Fluid friction: occurs as a pressurized fluid is restricted in its flow, causing heat

Sliding Friction Example

• Saddle of a lathe creates sliding friction as it moves along the ways
• Shaft rotating in a bushing

Rolling Friction

• Ball bearing meets rolling friction as it rolls around a bearing race

Fluid Friction

• Resistance one molecule in a fluid meets as it flows past another

Properties of Lubricants

• Viscosity: measurement of a fluid's ability to flow at a specific temperature
• Flash point: the temperature where a fluid's vapor will ignite when exposed to flame
• Fire point: when a fluid burns steadily once ignited once exposed to flame
• Pour point: the lowest temperature where a lubricant will pour freely

Choosing Oils Based on Viscosity

• Too low an oil viscosity: not provide adequate protection and ultimately poor reduction of sliding friction
• Too high a oil viscosity: cause fluid friction and elevated temperatures, and also poor lubrication protection

Oil Additives

• Anti-wear and EP agents: reduce friction and wear, and prevent scoring and seizure
• Corrosion and rust inhibitors: prevent corrosion and rusting of metal parts in contact with the lubricant
• Detergents: keep surfaces free of deposits
• Dispersants: keep insoluble contaminants dispersed in the lubricant
• Friction modifiers: alter the coefficient of friction
• Pour point depressants: enable lubricant to flow at low temperatures
• Seal swell agents: swell elastomeric seals
• Viscosity modifiers: reduce the rate of viscosity change with temperature

Lubricant Types

• Petroleum-based: incorporate molecules of hydrocarbons as well as additives
• Synthetic: lubricant bases are poly-alpha-olefins that contain no sulfur, metals, or phosphorus
• Animal by-product based: lards, fatty acids from cows, sheep, fish
• Vegetable-based: oils from vegetables like canola, olives

Lubricant Selection

• Petroleum-based, synthetic, animal by-product based, or vegetable-based lubricants
• Consider the type of machine tool, operating conditions, and the desired lubrication performance

Lubrication Types Commonly Found in the Machine Shop

• Liquids: oil that flows with viscosity of SAE 0 – 100
• Semi-solids: greases require some form of injection system

Lubrication Schedules

• Manufacturer's schedule: follow the recommended lubrication schedule
• Points to be lubricated: how often to lubricate, and what kind of lubrication to use
• Always lubricate as recommended by the manufacturer's lube chart