Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Identify and describe 5 common types of machine maintenance.
• Demonstrate correct lubrication procedures.
• Inspect machinery for signs of wear and tear.
• Apply lockout/tagout safety procedures.
• Explain the importance of maintenance records.

Lesson summary

Basic machine operations and maintenance are crucial for any aspiring Mechanical Technologist. These skills are not just theoretical; they directly impact the lifespan, efficiency, and safety of machinery used in South African industries, from agriculture and mining to manufacturing and construction. Properly maintained machinery reduces downtime, saves money on repairs, and ensures a safer working environment for everyone. Imagine a sugarcane farm in KwaZulu-Natal; without well-maintained tractors and harvesting equipment, the entire harvest could be lost.

Lesson notes

2. 1.

Types of Machine Maintenance: Understanding the different types of maintenance is crucial for efficient operations. Each approach has its pros and cons.

Preventive Maintenance (PM): This involves performing routine maintenance tasks at predetermined intervals (e.g., weekly, monthly, annually) to prevent breakdowns. Examples include lubricating parts, changing filters, inspecting components for wear, and tightening fasteners.

Benefits: Reduces breakdowns, extends machine life, improves safety.

Drawbacks: Can be time-consuming and costly, may involve unnecessary maintenance.

Example: Changing the oil and filter in a tractor every 250 hours of operation.

Predictive Maintenance (PdM): This uses sensors and data analysis to monitor machine condition and predict when maintenance is needed. Examples include vibration analysis, infrared thermography, and oil analysis.

Benefits: Minimizes downtime, reduces maintenance costs, allows for proactive repairs.

Drawbacks: Requires specialized equipment and expertise, can be expensive to implement.

Example: Using vibration analysis to detect an imbalance in a pump before it fails.

Corrective Maintenance (CM): This is performed to repair a machine after it has broken down.

Benefits: Restores machine functionality quickly.

Drawbacks: Can result in unexpected downtime, can be more expensive than preventive maintenance if the damage is extensive.

Example: Replacing a broken belt on a conveyor system.

Breakdown Maintenance (Run-to-Failure): This involves waiting for a machine to break down before performing any maintenance.

Benefits: Low initial cost.

Drawbacks: High downtime, increased repair costs, potential safety hazards. This is generally the least desirable approach.

Example: Waiting for a light bulb to burn out before replacing it (in a non-critical application).

Condition-Based Maintenance (CBM): Maintenance actions are determined based on the actual condition of the equipment, obtained through monitoring. This is similar to PdM but can also involve visual inspections and operator feedback.

Benefits: Optimal use of maintenance resources, minimizes downtime.

Drawbacks: Requires ongoing monitoring and analysis.

Example: Checking the coolant level in a vehicle and adding coolant only when needed, rather than on a fixed schedule. 2.

2. Lubrication: Proper lubrication is essential for reducing friction and wear, preventing corrosion, and dissipating heat.

Types of Lubricants: Oils and greases are the most common types of lubricants.

Oils: Used for high-speed applications where heat dissipation is important. They are graded by viscosity (resistance to flow). Higher viscosity oils are thicker.

Examples: SAE 10W-30 (for engines), hydraulic oil.

Greases: Used for low-speed, high-load applications where a thick lubricant is needed. They consist of oil thickened with a soap-based material.

Examples: Lithium grease (general-purpose), Molybdenum disulfide (MoS2) grease (for high-pressure applications).

Selecting the Correct Lubricant: Consult the machine's manual for the recommended lubricant type and grade. Factors to consider include operating temperature, load, speed, and environmental conditions.

Example: Using the wrong type of grease in a bearing can lead to premature bearing failure. If the manual specifies lithium grease, using a calcium-based grease may not provide adequate lubrication.

Lubrication Procedures: Clean the area around the lubrication point. Use the correct type of applicator (e.g., grease gun, oil can). Apply the lubricant according to the manufacturer's instructions. Wipe away any excess lubricant. 2.

3. Inspection for Wear and Tear: Regularly inspecting machinery for signs of wear and tear can help identify potential problems before they lead to breakdowns.

Common signs of wear include: Cracks: Can indicate structural weakness.

Leaks: Can indicate worn seals or damaged components.

Unusual Noises: Can indicate loose parts, worn bearings, or other problems.

Excessive Vibration: Can indicate imbalance or misalignment.

Overheating: Can indicate insufficient lubrication or excessive load. 2.

4. Lockout/Tagout (LOTO): Lockout/tagout procedures are used to prevent accidental startup of machinery during maintenance.

Procedure: Identify all energy sources (electrical, mechanical, hydraulic, pneumatic, etc.). Notify all affected personnel. Shut down the machinery. Isolate all energy sources (e.g., disconnect electrical power, close valves). Lock out and tag out all energy isolating devices. The lock and tag must be unique to the person performing the maintenance. Verify that the machinery is de-energized. Perform the maintenance. Remove locks and tags after the maintenance is complete. Notify all affected personnel before restarting the machinery. 2.

5. Maintenance Records: Keeping accurate maintenance records is essential for tracking machine performance, identifying trends, and planning future maintenance.

Information to Record: Date and time of maintenance.