Materials in Engineering

Materials in Engineering

• Materials serve as a basis in engineering and are classified into four main categories.

Metals

• Examples include Steel, aluminum and copper.
• Have high strength, ductility, conductivity for heat, and conduct electricity.
• They are used in structures, machinery, and electrical cables.

Polymers

• Plastics, rubber, and PVC are examples.
• They are of low density, flexible, corrosion-resistant.
• Polymers are used in packaging, pipes, and electronic components.

Ceramics

• Glass, porcelain, and bricks are examples.
• Known for high hardness, resistance to heat and corrosion, and brittleness
• They are used as insulators, coatings, and cutting tools.

Composites

• Fiberglass, carbon fiber, and reinforced concrete are examples.
• Combine properties of two or more materials.
• They are used in aeronautics, automotive, and construction.

Mechanical Properties of Materials

• Describe how materials behave under external forces.

Resistance

• The ability to withstand loads without deformation or fracture.
• Tensile, compression, bending, and torsion are types of resistance.

Hardness

• Resistance to plastic deformation or scratching.
• Measured using the Mohs scale (for minerals).

Elasticity

• Is the ability to recover original shape after deformation; rubber is an example.

Plasticity

• The capacity to deform permanently without breaking.
• This is important in processes like forging and extrusion.

Tenacity

• The capacity to absorb energy before fracturing.
• It is related to impact resistance.

Brittleness

• Is a tendency to fracture without significant plastic deformation, such as glass does.

Physical Properties of Materials

• Physical properties describe inherent characteristics of materials
• Density defines mass per unit volume which is important where weight is critical, like in aeronautics
• Thermal Conductivity describes the ability to transfer heat; for example, metals like copper are good conductors.
• Electrical Conductivity describes is the ability to allow the flow of electricity; copper and aluminum are widely used in cables.
• Thermal Expansion is changes in dimensions with temperature, which is an important consideration when designing structures and components.
• Magnetic Properties relates to the ability to be attracted by a magnet or generate magnetic fields; iron and nickel are examples.
• Optical Properties relates to behavior in the presence of light (transparency, reflection, refraction); glass is an example used in lenses and windows.

Composite Materials

• Composite materials are made up of two or more materials with different properties, which improves the characteristics of the final material when combined.

Components

Matrix

• Matrix is the base material that supports and distributes loads (e.g., polymers, metals, ceramics).

Reinforcement

• Reinforcement provides strength and stiffness (e.g., fibers of glass, carbon, aramid).

Types of Composite Materials

Fiberglass

• It is a polymer matrix reinforced with glass fibers.
• It is used in boat hulls and automobile panels.

Carbon Fiber

• It is a polymer matrix reinforced with carbon fibers.
• It is used in aeronautics and sports equipment.

Reinforced Concrete

• It is concrete matrix reinforced with steel bars.
• It is used in the construction of buildings and bridges.

Advantages

• High strength and stiffness with low weight.
• Resistant to corrosion and fatigue.
• They have customizable design according to needs.

Challenges

• Some materials are expensive (e.g., carbon fiber).
• The manufacturing process can be complex.

Textile Industry: History and Health and Safety

• The textile industry includes processes of spinning, weaving, dyeing, and finishing utilizing both natural and synthetic fibers.
• Technological advances have transformed textile production from artisanal to industrial, impacting the economy and international trade.
• Safety and health issues include mechanical risks, exposure to toxic substances, and work stress, alongside environmental problems related to emissions and waste.

Global Trends in the Textile Industry

• There is a constant increase in the demand for textile products, with a trend towards automation and production shifting to developing countries.
• Synthetic fibers are gaining dominance, and the safety and occupational health of textile workers are growing concerns in developing countries.
• Asia-Pacific region accounts for approximately 70% of global textile and apparel production.

Cotton Production and Ginning

• Cotton production involves soil preparation, pest and disease control, and harvesting, whether manual or mechanical.
• Ginning, separates lint from seed; it must balance product quality with fiber preservation using specific machinery and humidity control.
• Workplace hazards in ginning include machinery-related injuries and dust exposure, requiring safety measures, PPE, and employee involvement in safety programs.

Production of Cotton Yarn

• Spinning transforms raw cotton into yarn through opening, mixing, cleaning, carding, drawing, roving, and spinning processes.
• Spinning machinery presents accident risks, and inhalation of cotton dust can lead to byssinosis, requiring dust control, PPE, and safety management systems.
• Noise is a notable risk, mandating hearing protection programs; heat stress requires temperature and humidity controls.

Wool Industry

• The wool industry employs carding and combing systems to produce various yarn and fabric types, blending new and recycled wool.
• Mechanical injuries from machinery, dust inhalation, fire risk, and chemical exposure are risks that require protection, ventilation, and PPE.
• Health issues like anthrax, dermatitis and respiratory conditions should be prevented through hygiene, chemical product control and ventilation systems.

Silk Industry

• Silk production includes sericulture, spinning, twisting, degumming, bleaching, weaving, and dyeing.
• Risks include carbon monoxide poisoning, dermatitis from raw silk handling, and respiratory issues from bacteria and protein aerosols.
• Prevention focuses on temperature and humidity control, ventilation, good hygiene practices, and medical check-ups.

Viscose (Rayon)

• Rayon is manufactured from chemically treated cellulose through multiple processes.
• Main risks are exposure to carbon disulfide and hydrogen sulfide, which can cause serious health problems.
• Prevention requires strict monitoring of gas levels, machinery encapsulation, and PPE use.

Synthetic Fibers

• Synthetic fibers are created from synthetic polymers of chemical elements or petrochemical compounds.
• Major types are polyamides (nylon), polyesters, polyvinils, polyolefins, and polyurethanes.
• Risks include machinery accidents, fires, explosions from flammable materials, and poisoning from solvents and toxic chemicals.

Natural Felt Products

• Felt is made by interlacing fibers of skin, hair, or wool through heat, moisture, and friction.
• Risks include accidents from machinery, noise, dust inhalation, chemical exposure, and fire hazards.
• Prevention centers on protecting machinery, ensuring adequate ventilation, using PPE, and applying fire prevention measures.

Dyeing, Printing and Finishing

• Dyeing uses a variety of dyes and processes based on the fabric, whereas printing is done with cylinder machines.
• Risks include fire and explosion from flammable solvents, chemical risks from hypochlorite, corrosive acids and alkalis, and organic solvents.
• Finishing involves mechanical and chemical treatments to modify fabric texture and appearance, with risks including heat, roller contact, and formaldehyde exposure.

Nonwoven Textiles

• Nonwovens are manufactured through various processes, such as spun bonding, melt blowing, and dry or wet laying.
• Risks include noise, airborne particles, chemicals for binding fibers, and hazardous work surfaces.
• Machinery use requires training, PPE, and ventilation to avoid exposure to hazardous substances.

Weaving and Knitting

• Weaving and knitting are primary methods of fabric production, done with automated electric machines.
• Risks in weaving include falls, machinery entanglements, handling heavy materials, and fires.
• Health risks involve hearing loss from noise and respiratory conditions related to fibers, requiring hearing protection and dust control.

Carpets and Rugs

• Carpets are made using knotting or weaving techniques, utilizing natural and synthetic fibers.
• Production involves fiber extrusion, dyeing, and finishing, with risks related to machinery and chemical contact.
• Safe work practices include machine guards, safety training, and ergonomic and chemical exposure controls.

Hand-Woven or Knotted Carpets

• Hand-woven carpets are made in domestic workshops where working conditions can be precarious.
• Risks include skeletal deformations from uncomfortable postures, visual problems, hand and finger injuries, stress, and chemical exposure.
• Preventive measures include improving lighting, ventilation, ergonomics, and sterilizing wool, as well as controlling chemical products.

Respiratory and Other Conditions Observed in the Textile Industry

• The textile industry has been associated with respiratory conditions like byssinosis, textile fevers, and chronic bronchitis.
• Byssinosis is characterized by chest tightness at the start of the work week, while textile fevers present with hyperthermia and cough.
• Other occupational hazards linked to textile work include colorectal and bladder cancer, musculoskeletal disorders, and exposure to dimethylformamide and carbon disulfide.

Food industry

Overview of the Food Industry

• The food industry encompasses a variety of industrial activities focused on the treatment, transformation, preparation, conservation, and packaging of food products.
• These activities utilize raw materials of plant or animal origin, sourced from agricultural, livestock, and fishing operations.
• The industry has seen significant diversification, ranging from small family businesses to large mechanized industrial processes.

Processes in the Food Industry

• The processes in the food industry can be divided into several stages: handling and storage of raw materials, extraction, processing, preservation, and packaging.
• Raw material handling has become mechanized to reduce manual intervention, employing technologies such as conveyor belts and automated systems.
• Storage is crucial, especially in seasonal industries, and is carried out in silos and refrigerated chambers, tailored to the characteristics of the products.

Health Effects and Pathological Guidelines in the Food Industry

• Workers in the food industry may be exposed to various risks, including infections and diseases derived from food handling.
• Maintaining strict hygiene controls is essential to ensure product quality and protect consumer health.
• Working conditions, such as heat and humidity in cooking operations, can also affect worker health, leading to risks such as heat stroke.

Environmental Protection and Public Health

• Environmental protection and public health issues are critical in the food industry.
• Proper waste management, emission control, and prevention of leaks of hazardous substances, such as ammonia in refrigeration systems, are essential to minimize environmental impact and protect community health.
• Modernizing techniques and processes is necessary not only to increase production but also to ensure a safe and healthy work environment.

Sectors of Food Production

Meat Industry

• Responsible for processing beef, sheep, pork, and poultry.
• It turns meat into consumer-ready products and ensures good quality and safety.
• It is important to follow hygiene regulations and use preservation techniques to avoid contamination.

Poultry Industry

• It produces and processes birds, mainly chickens and turkeys.
• This sector provides high-quality proteins to the population.
• People should consider animal welfare as well as proper handling practices to make sure the products are healthy.

Dairy Industry

• This division is involved in the production of products with milk, like cheese, yogurts or butter.
• Its main role is to make the milk safe. Pasteurization and storage conditions are important to maintain the quality.

Cocoa Products and Chocolate Industry

• This sector dedicates itself to the alteration of cocoa beans into chocolate products that are in high-demand.
• Sustainability in coca production and labor conditions for farmers should be considered.

Cereal-Based Products

• Cereals and their derivatives such as bread, pasta or breakfast cereals belong to this sector. They are aimed at providing basic and nutritious items.
• Considering constituent's quality and safety of the production process is key to ensure alimentary safety.

Bakeries

• Bakeries exist to sell fresh breads and other products.
• Hygiene inside the elaboration process, correct storage is key to keep the freshness.

Sugar Beet Industry

• Refines sugar content from sugar-beets.
• Provides vital components that are present in alimentary products.
• Cultivation methods and sustainable production must be taken into account.

Oils and Fats

• Extracts and refines both the vegetable and animal oils and oils.
• Main goal to add essential goods so cooking and factory-made alimentary production improves. Methods of extraction and standards for pureness should be considered.

Food Industry Processes

• Handling and Storage: Highlight the use of mechanical equipment and adequate storage space for items and finished production.
• Extraction: Methods to remove nourishment such as crushing and milling.
• Conservation and Packaging: Technology assures that the standard and safety are maintained, to supervise temperature and humidity.