Introduction to Manufacturing Systems and Processes

Posted on Sep 18, 2024 in Other subjects

ITEM 1 – MANUFACTURING SYSTEMS

Concept of Industrial Process Machinery

A process is a set of ordered activities aimed at achieving a particular goal. In industrial engineering, the concept of process is crucial because the practice of this field requires planning, integrating, organizing, directing, and controlling.

These activities enable engineers to achieve their objectives in their profession. They should consider production processes as a tool for designing and defining plans, programs, and projects related to system design, integration, organization, management, and control. This includes optimization work, result evaluation, setting quality standards, increasing efficiency, and implementing control mechanisms.

Manufacturing Concept

  • Work done by hand or with machines as auxiliaries.
  • A designated place where all activities are organized and planned for the transformation of materials into useful items or services for society.

Manufacturing and Engineering

Engineers must view manufacturing as a mechanism for transforming materials into useful items for society. It is also considered the structure and organization of actions that enable a system to achieve a specific task.

Classification of Manufacturing Processes

Manufacturing processes are classified into three groups:

  • Processes that change the shape of the material: casting or molding, forming by cold and hot deformation, and powder metallurgy.
  • Processes that remove material: machining using metal cutting machines and non-conventional machining techniques.
  • Surface finishing processes: achieved by removing particles (abrasive processes) and applying coatings.

For these processes to be useful to engineers, the following criteria should be considered:

  • Economic production criteria for profit:
  • Cost: must be acceptable and competitive.
  • Profitability: should provide returns superior to those offered by banks.
  • Quality: only the necessary level of quality should be pursued.
  • Economic production criteria for effectiveness:
  • Project: must have a functional design that allows for calculated and controlled manufacturing.
  • Materials: selection of appropriate and economically acceptable materials.
  • Manufacturing process: the system for processing materials with a predetermined quality, considering customer needs efficiently and economically.
  • Human factors: motivation, treatment, facilities, training, and safety.
  • Administrative process: planning, integration, organization, direction, and control.

Effectiveness and Efficiency

Efficiency is the numerical relationship between the amount achieved by a system and the maximum amount the system can achieve.

Effectiveness is the evaluation of the objectives, purposes, or functions of a system or process without any numerical assessment or predetermined standards.

ITEM 2 – INTRODUCTION TO MANUFACTURING PROCESSES

Production Systems

Manufacturing takes place within production systems with diverse characteristics. These systems involve numerous interactive elements aimed at producing a specific product. These production elements can be grouped within a single facility (factory or plant), a department within it, or distributed across multiple plants or departments.

Organization of Production Systems

Every production system consists of an input of raw materials, including energy, and an output of products. Between these extremes, there are material flows that undergo a series of processes. These materials are transformed by the system’s elements (machines, storage, transportation, etc.) to acquire the properties specified in the design.

Process Flow

It is common to classify manufacturing processes based on the rate of material flow throughout the process. Continuous production systems, also known as process systems, are those in which the material route through the system remains constant. They utilize few raw materials and produce few or unique products, typically measured by weight (tons) or volume (m3). These systems are characterized by high costs, rigidity, limited tolerance for process changes, and a high degree of automation.

Characteristics of Production Systems for Intermediate Products or Commodities

Examples include the steel industry, oil refining, cement production, paper manufacturing, and the processing of unprocessed foods like flour and sugar.

Discrete Production Systems

Also known as “job shops,” these systems are geared towards manufacturing a variety of different products. They are characterized by their flexibility in both machinery and organization. They are organized by departments (machining, heat treatment, assembly, etc.) and are challenging to automate. Products are measured in parts or units, with quantities typically being low. The wide range of products and raw materials used leads to one of the biggest challenges in these systems: coordinating logistics.

Combined Systems

While purely continuous or job shop systems may exist in practice, most production systems fall somewhere in between.

Closer to the continuous end of the spectrum are assembly systems. Commonly used in automobile or appliance manufacturing, these systems rely on assembly lines that are more or less automated. These systems are inherently rigid, but the increasing use of computers and robotics has significantly enhanced their flexibility.

Closer to the job shop end of the spectrum are batch manufacturing systems. These systems produce products in batches of a limited number of units, ranging from tens (e.g., aerospace and rail sectors) to hundreds (e.g., electronic equipment and industrial machinery).

Flexible Manufacturing

This is the current trend in consumer goods manufacturing and is gradually replacing traditional production planning concepts. It involves moving away from long-term sales forecasts and mass production towards supplying demand by manufacturing the smallest possible batches based on short-term sales forecasts (monthly, weekly, daily, etc.). This approach allows for financial savings in fixed capital, raw materials, personnel, equipment, and storage. Computer-controlled equipment (Computer Numerical Control, CNC) and the organization of flexible manufacturing cells have enabled the combination of flexibility and high productivity in this process.

Phase, Subphase, and Operation

The organization of the manufacturing process is based on its logical subdivision, aligned with the pursued objectives. The following sequence is commonly used:

  • Phase: A set of technologically related transformations performed on the product using the same machine, plant, equipment, workstation, or sometimes a group of them. For example, in a machining process, turning, milling, or planing could each be considered a phase.
  • Subphase: Sometimes, different stages within a phase can be distinguished. For instance, in a machining operation on a lathe, different part positions or operation types could represent distinct subphases.
  • Operation: Each elementary task that can be carried out on a machine or workstation performing a specific process. Operations can be productive, causing actual changes in materials (e.g., stamping or turning), or non-productive, necessary for the process but not directly altering materials (e.g., movements, tool changes, storage, machine preparation).

Relationship Between Design and Manufacturing

The time required for product design directly impacts costs and, consequently, a company’s market position.

Product design should consider both functional requirements (quality, durability, safety) and economic aspects, market demands, manufacturing methods, and necessary processes. These factors are interconnected and should be considered holistically.

Currently, there is a strong emphasis on minimizing design time and costs by optimizing available resources as efficiently as possible. This approach, known as simultaneous or concurrent engineering, aims to reduce both design time and expenses.

Manufacturing Costs

The production cost of a product encompasses all expenditures incurred to make it ready for sale. The various aspects that constitute the product cost structure are defined as follows:

  • Product design: functional requirements, market demand, life cycle, and forecasting of future changes.
  • Material selection: mechanical and physical properties, geometrical properties, manufacturability, supply reliability, and material cost.
  • Process definition: process feasibility, influence on material properties, production volume, automation level, assembly type, and final cost.

Manufacturing Time

Manufacturing involves a series of steps, each consuming a certain amount of time. The total time required to manufacture a single product unit is called the unit manufacturing time. Minimizing this value is a priority for achieving competitive product pricing. The following components can be distinguished:

  • Uptime: Also known as transformation time. This is the time during which materials undergo actual transformation processes.
  • Downtime: This time is inevitably incurred during the manufacturing process but does not involve changes to the materials. Due to their different nature, machine preparation time and operation time are considered separately. Operation time, in turn, includes the time spent on part and tool placement and replacement.

The sum of processing and maneuvering times is referred to as machine time and represents the total time a workpiece spends on the machine undergoing machining operations. This is also called machining time.