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

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

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" »

Resource Optimization & Sustainable Practices

Features:

• Use of materials with decreased manufacturing waste.
• Use of materials that can be recycled.
• Decreased consumption of strategic materials.

Benefits of Resource Optimization

This approach, in turn, leads to:

• Replacement of metals and their alloys with polymers.
• Metal alloys offer superior mechanical resistance and better corrosion response.
• Increased use of new metals and light alloys.

Understanding Natural Resources

A natural resource is anything that humanity derives from nature to meet its needs.

Types of Natural Resources

Non-Renewable Resources

Resources that exist in limited quantities and can be exhausted, such as oil.

Renewable Resources

Resources that are not exhausted, such as wind and sunlight.... Continue reading "Resource Optimization & Advanced Technologies" »

Diode Bias: Direct and Reverse

A diode conducts electrical current only when its terminals are connected to the poles of a generator. It is then said that the diode has a bias and is in a state of conduction. If connected backwards, it is reverse biased and is in a state of deadlock, since no current passes.

Commercial Diodes

The symbol of the diode is an arrow indicating the direction in which the current can traverse. Germanium diodes have transparent encapsulation, and the line indicating the negative terminal is red.

Diode Rectification

The current that supplies the power grid, which we can access by connecting an apparatus to a plug, is common alternating current (AC). It is characterized by its polarity, which is continually changing 50 times... Continue reading "Diode Operation, Rectification, and Semiconductor Basics" »

Introduction to Electronic Media Technology

Electronic media technology involves the use of microelectronics to create, retrieve, and report information.

Evolution of Computing

Early electronic components faced challenges: resistances impede the passage of current, while capacitors store electrical charge. Inductors are typically copper wires wound into a coil. Early vacuum tubes, metal cylinders covered by glass tubes, regulated the flow of electrons.

The evolution of computers can be summarized by generations:

• 1940s (1st Generation): Computers used vacuum tubes.
• 1950s (2nd Generation): Transistors and semiconductors appeared.
• Late 1950s - 1960s (3rd Generation): Integrated circuits were developed.
• 1969: ARPANET (connecting computers) was established.

Testing Properties of Materials

Conformation

Used to know the degree of suitability of materials to manufacture parts.

Features

Used to know the mechanical characteristics of metal.

Understanding the Mechanical Properties of Materials

Used to find out the mechanical properties of materials.

Defects

Used to verify that there are no defects in the parts.

Mechanical Properties

• Hardness
• Tensile strength
• Yield strength
• and so on

Types of Hardness Measurements

• Scratch
• Penetration
• Rebound

Penetration Methods

• Brinell: A steel ball is used as the indenter, and the measurement is the area that the steel ball leaves.
• Rockwell: A diamond-tipped conical tip is used for hard materials, and a spherical tip is used for soft materials. Hardness is found by measuring the depth

Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT)

Activity Duration and Delays

If an activity's slack (MTIJ) equals zero, any delay in this activity will delay subsequent activities. However, activities can not delay the project if MTIJ is greater than zero.

Critical Path

The critical path is the longest path, which represents the minimum time necessary to complete the project. Activities on the critical path are called critical activities.

Activities with Uncertain Duration

When the duration of activities is not known with certainty, three estimates are used: optimistic (a_ij), realistic (m_ij), and pessimistic (b_ij). It is assumed that the duration of activities follows a beta distribution. Assuming t_ij are independent... Continue reading "Project Management & Optimization: CPM, PERT, Network Flow, & Integer Programming" »

Piston Verification: Ensuring Optimal Engine Performance

Checking Piston Sliding Zones

Inspect the sliding zones of the piston. There should be no signs of jamming or excessive friction.

Weight Difference Between Pistons

Use a balance to compare the weight of each piston. Differences up to 4 grams are allowed. Larger differences can cause crankshaft imbalance and vibrations.

Piston Diameter

Pistons are not perfectly cylindrical. Follow the manufacturer's instructions to measure the diameter at the specified zone, usually at a certain distance from the head, measured transversally at the same height as the bolt. The installation clearance between the piston and cylinder compensates for thermal expansion and is typically between 0.02 and 0.05 mm.

Bolt