Notes, summaries, assignments, exams, and problems for Technology

Mechanical Principles

Lever: $F \cdot d_1 = d_2 \cdot R$

Wheel: $F = (N \cdot \text{coefficient}) \cdot r_1$

Screw: $R = 2 \pi F \cdot \text{performance} \cdot p$

Moment: $M = F \cdot d$

Fixed Joints

Riveted Joints:

Used when joining flat pieces of a certain thickness where welding might cause internal tensions. They are used for riveting or welding parts.

• Lap Joints (Unions coatings): Where the two pieces overlap.
• Butt Joints (Unions for cobrejuntes): Where the two pieces are on the same plane and are linked together by a single plate riveted to both pieces.
• Double Cover Butt Joints (Joints with two cobreguntes): When the pieces are in the same plane and are linked together by two plates riveted, one on each side.

Detachable Joints

Screw (Bolt and Nut)

Material Hardness: Resistance to Deformation

Hardness is the resistance a material offers to being penetrated or scratched by another material. This property is primarily due to the cohesive forces between the atoms of the material. Hardness is compared and measured using various types of tests.

Generally, the more penetration achieved by applying the same force, the softer the material being studied will be.

Brinell Hardness Test

The Brinell hardness test uses a hard spherical indentor, typically made of tungsten carbide, which is situated above the sample material to be tested. A specific load is applied to the sphere for a defined period. After removing the load and the indentor, the diameter of the indentation left on the specimen is measured... Continue reading "Understanding Material Properties: Hardness, Toughness, Fatigue, Thermal" »

Command Devices and Circuit Control

These devices are responsible for the circuits that govern the electrical enclosure and execute the functions for which they were designed.

Disconnectors

Their function is to keep the circuits separate from the power source, typically for maintenance or repairs.

Load Switch

A manually operated device that can open and close the circuit under load.

Electrical Protection Devices

These devices detect and eliminate disturbances caused by the abnormal functioning of the electrical installation.

Most Frequent Anomalies

• Overcurrents

  Caused by overloading or short circuits, resulting in higher than normal power consumption.

• Electrical Contacts

  Occur when persons or animals come into contact with the installation, causing the

Building Material Characteristics

Flooring Materials

Ceramic Flooring

• Formed by mixing water and clay, then molded and baked.
• A glazed layer of silica and aluminum is applied to the smooth surface, providing enamel-forming qualities such as resistance and impermeability, meeting standards like GCN 1400.

Terrazzo

• Consists of white cement mixed with chunks of marble and granite, compacted and vibrated before curing.
• Pros: Economical, durable, brilliant color after grinding/polishing.
• Cons: Can be slippery, requires more labor.

Hydraulic Tiles

• Consist of two layers: the lower layer is a lean mixture of sand and cement, while the upper layer contains marble sand or silica and Portland cement.

Types of Flooring

• Terrazzo tiles
• Porcelain tiles
• Ceramic tiles
• Extruded

Mechanical Fasteners and Machine Elements

Riveted Joints

Riveting is a method for joining flat pieces of thin material without welding. A rivet, which has a pre-formed head on one end, is inserted into pre-drilled holes in the pieces to be joined. The other end of the rivet is then deformed (e.g., by hammering or pressing) to create a second head, securely fastening the components.

Common applications include:

• Lap Joints: Where two pieces overlap.
• Butt Joints: Where pieces are in the same plane and joined by a single cover plate (riveted).
• Double Cover Plate Butt Joints: Using two cover plates, one on each side, riveted to the main pieces.

Cotter Pins

Cotter pins are steel components designed to be inserted into specific notches, recesses, or holes... Continue reading "Essential Machine Elements: Fasteners, Springs, Bearings, and Lubricants" »

Products and Services Defined

Goods

Goods are all products that have measurable physical characteristics.

Services

Services are intangible and immaterial products.

Economic Sectors of Companies

Primary Sector Companies

These companies are engaged in activities directly related to the land, such as: agriculture, mining, fisheries, and livestock.

Secondary Sector Companies

These are companies that transform, modify, and process raw materials to create the final product.

Tertiary Sector Companies

These companies offer customer services, including:

• Trade
• Transport
• Banking
• Other services

Company Ownership and Legal Forms

Public Company

A public company is managed and directed by government institutions.

Private Company

A private company is managed and directed by a... Continue reading "Business Structures and Production Management Essentials" »

Surgical Wound Care Principles

Surgical wounds are typically managed under clean and aseptic conditions. In contrast, other wounds, such as those resulting from firearms or animal bites, are considered "dirty wounds" due to a higher risk of contamination.

Objectives of Wound Management

• Remove or prevent bleeding.
• Encourage wound healing (cicatrization).
• Prevent infection.
• Promote the drainage of secretions.

Wound Care Methods

Open Method:

No dressings are used. Only cleaning and asepsis of the wound are performed, leaving it exposed to dry.

Closed Method:

Aseptic cleaning of the wound is performed, and dressings are applied and secured.

Essential Elements for Wound Care

• For Cleaning and Asepsis: Saline solution, sterile water or sterile soap solution, gauze

Mechanical Cutting Tools

Sierra Alternative and Band Saws

Sierra Alternative: This tool is intended for cutting large pieces or for series production with a minimum contribution of heat.

Band Saw: This features a circular saw supported by two rollers that move in circles by the action of a motor. The rotation speed is adjustable, and it is cooled using taladrina (coolant).

Jigsaws and Manual Cutting Tools

Jigsaw: Used in the repair of bodywork (carrocería), it allows you to work on almost any surface, moving between 200 and 250 beats per minute.

Grounds and Stocks: This manual mechanical cutting tool converts rotary movement into a back-and-forth motion.

Thermal and Abrasive Cutting

Oxy-fuel and Plasma Cutting

Oxy-fuel Cutting (Oxitall): Used for steels,... Continue reading "Industrial Metal Cutting and Finishing Tools" »

Workplace Safety: Personal Protective Equipment (PPE)

Hand Protection: Gloves and Their Risks

When handling a stock of spare parts, mechanical risks are primarily associated with the transport of parts, whether packed or unpacked. The main hazards include cuts from sharp edges or splinters from pallets.

Gloves for Mechanical Hazards

Gloves designed for mechanical hazards should offer good dexterity, tactile sensitivity, and cut protection. While some welding gloves provide thermal resistance, their primary function is often mechanical and thermal protection.

Gloves for Chemical Hazards

These types of gloves must meet specific minimum mechanical properties to bear the CE marking, ensuring they provide adequate protection against chemical exposure.... Continue reading "Workplace Hazard Control and Personal Protective Equipment" »