Engineering Design Process and Preparation of Working Drawings for SS 3

Class: SS 3
Term: First Term
Week: 2
Age: 17 years
Duration: 60 minutes
Subject: Technical Drawing
Previous Lesson: Freehand Sketching of Builders’ Hand Tools
Topic: ENGINEERING DESIGNS AND WORKING DRAWING
Subject Matter: engineering design process and preparation of working drawing e.g. plans elevations etc teacher: explains engineering design processes guides students to design useable engineering items e.g. funnels, opener sparer etc guides student in the preparation of engineering working drawings student: select and deign a useable engineering item preparer the working drawing of chosen item teaching materials drawing instruments and model

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Define engineering design.
• Explain the stages of the engineering design process.
• Identify different types of working drawings.
• Describe the purpose of working drawings.

Affective Domain

• Appreciate the importance of systematic design in engineering.
• Demonstrate precision and neatness in preparing technical drawings.

Psychomotor Domain

• Apply the engineering design process to design a simple engineering item.
• Prepare a working drawing (e.g., plan, elevation) of a designed item.

Reference Materials

The following resources were used in planning this lesson:

• 2014 Senior Secondary Education Curriculum (SSEC)
• Relevant State Unified Scheme of Work
• Technical Drawing textbooks for Senior Secondary Schools
• FCT ERC/NAPPS Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Drawing board
• T-square
• Set squares (30/60 and 45 degrees)
• Pencils (HB, H, 2H)
• Eraser
• Compass
• Protractor
• Divider
• Drawing paper
• Models of simple engineering items (e.g., funnel, bottle opener, spanner)

Rationale for the Lesson

This lesson is important for students to understand the systematic approach used in creating functional products. It equips them with the foundational knowledge and practical skills required to translate design ideas into clear, manufacturable instructions through working drawings. This understanding is essential for further studies in engineering and technical fields.

Prerequisite/Previous Knowledge

Students should have basic knowledge of technical drawing instruments and their uses, as well as an understanding of orthographic projection principles.

Lesson Content/Board Summary

ENGINEERING DESIGNS AND WORKING DRAWING

Engineering Design Process

Engineering design is a systematic approach to problem-solving in engineering, aimed at creating new products, systems, or processes, or improving existing ones, to meet specific needs or solve identified problems.

Stages of the Engineering Design Process

1. Problem Identification/Need Assessment: Clearly defining the problem or need that the design aims to address. This involves understanding user requirements and constraints.
2. Research and Information Gathering: Collecting relevant data, existing solutions, materials, and technologies. This helps in understanding the scope and potential solutions.
3. Conceptual Design/Brainstorming Solutions: Generating multiple ideas and concepts to solve the identified problem. This stage focuses on creativity and exploring various possibilities.
4. Detailed Design and Analysis: Developing the chosen concept into a detailed design, including specifications, dimensions, materials, and components. Analysis (e.g., stress, cost) is performed.
5. Prototyping and Testing: Building a physical or virtual model (prototype) of the design and testing its functionality, performance, and durability against the initial requirements.
6. Evaluation and Refinement: Analysing test results, identifying shortcomings, and making necessary modifications or improvements to the design. This is an iterative process.
7. Implementation/Production: Manufacturing or constructing the final product based on the refined design.
8. Documentation: Creating comprehensive technical drawings (working drawings), reports, and manuals that fully describe the design for manufacturing, assembly, and maintenance.

Working Drawings

Working drawings are detailed technical drawings that provide all the necessary information for the manufacture, construction, or assembly of a product or component. They serve as a comprehensive visual and textual guide for engineers, technicians, and manufacturers.

Purpose of Working Drawings

1. To communicate design intent clearly and unambiguously.
2. To provide precise dimensions, tolerances, and material specifications.
3. To guide manufacturing, assembly, and installation processes.
4. To serve as legal documents for contracts and quality control.
5. To facilitate maintenance and repair of the product.

Types of Working Drawings

1. Orthographic Projection Drawings: These show multiple views of an object from different angles, typically a front view, top view (plan), and side view (elevation).
   1. Plan: The view of an object as seen from directly above.
   2. Front Elevation: The view of an object as seen from the front.
   3. End Elevation: The view of an object as seen from the side (either left or right).
2. Detail Drawings: Show individual components or parts of an assembly with all their specific dimensions, features, and manufacturing information.
3. Assembly Drawings: Illustrate how different components fit together to form a complete product or system, often showing part numbers and a bill of materials.
4. Schematic Diagrams: Represent systems (e.g., electrical, hydraulic, pneumatic) using standardised symbols to show connections and functional relationships rather than physical appearance.

Preparation of Working Drawings

The preparation of working drawings requires adherence to specific principles and standards to ensure clarity, accuracy, and completeness:

1. Accuracy and Precision: All lines, dimensions, and features must be drawn with exactness to avoid errors in manufacturing.
2. Clarity and Legibility: Lines should be distinct, text clear, and symbols easily understandable. Use appropriate line types and thicknesses.
3. Completeness: The drawing must contain all necessary information, including dimensions, tolerances, surface finishes, material specifications, and any special instructions.
4. Standardisation: Adherence to national or international drawing standards (e.g., ISO, BS, ANSI) ensures universal understanding and consistency.
5. Proper Layout and Scale: The drawing should be well-organised on the sheet, using an appropriate scale to represent the object clearly.
6. Use of Drawing Instruments: Proper use of T-square, set squares, compass, protractor, and pencils is essential for producing professional-quality drawings.

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Guided Practice, Question and Answer, Explanation, Practical Activity, Individual Practice

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Engaging/Recalling

Teacher’s Activity: The teacher greets the students and asks them to recall what they know about technical drawing and its importance in everyday life. The teacher then introduces the topic: Engineering Designs and Working Drawings.

Pupils’ Activity: Pupils respond to questions and listen attentively to the introduction.

Learning Point: Importance of technical drawing

Step 2: Explanation of Engineering Design Process

Time: 10 minutes

Teaching Skill: Explanation/Illustration

Teacher’s Activity: The teacher explains the concept of engineering design as a systematic problem-solving process. The teacher then outlines and explains each stage of the engineering design process, using simple, relatable examples.

Pupils’ Activity: Pupils listen, ask questions for clarification, and take brief notes.

Learning Point: Engineering design process stages

Step 3: Discussion on Design Examples

Time: 10 minutes

Teaching Skill: Discussion/Guidance

Teacher’s Activity: The teacher guides students to discuss how familiar items (e.g., a chair, a water bottle, a simple tool) might have gone through an engineering design process. The teacher encourages students to think about the problems these items solve.

Pupils’ Activity: Pupils participate in the discussion, offering examples and insights.

Learning Point: Real-world design examples

Step 4: Introduction to Working Drawings

Time: 5 minutes

Teaching Skill: Explanation/Definition

Teacher’s Activity: The teacher defines working drawings and explains their purpose in communicating design information for manufacturing. The teacher shows examples of working drawings (if available) or sketches on the board.

Pupils’ Activity: Pupils observe the examples and listen to the explanation.

Learning Point: Purpose of working drawings

Step 5: Types and Preparation of Working Drawings

Time: 10 minutes

Teaching Skill: Categorisation/Demonstration

Teacher’s Activity: The teacher explains different types of working drawings, focusing on plans and elevations. The teacher demonstrates the basic principles of preparing working drawings, emphasising accuracy, clarity, and completeness.

Pupils’ Activity: Pupils observe the demonstration and note the types and principles.

Learning Point: Types of working drawings

Step 6: Guided Design and Drawing Practice

Time: 10 minutes

Teaching Skill: Guided Practice/Supervision

Teacher’s Activity: The teacher guides students to select a simple engineering item (e.g., a funnel, a simple spanner model) and begin to sketch its plan and front elevation. The teacher moves around to provide individual assistance and corrections.

Pupils’ Activity: Pupils select an item and attempt to sketch its plan and elevation under the teacher’s guidance.

Learning Point: Sketching plans and elevations

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is engineering design?
2. Mention three stages of the engineering design process.
3. What is the main purpose of a working drawing?
4. Name two types of working drawings.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Understanding design and drawings

Step 8: Note-Taking

Time: 10 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on engineering design process and working drawings into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording lesson information

Step 9: Conclusion

Time: 5 minutes

Teaching Skill: Summarising/Reinforcement

Teacher’s Activity: The teacher summarises the key points of the lesson, reiterating the importance of systematic design and accurate working drawings in engineering. The teacher encourages students to practise drawing at home.

Pupils’ Activity: Pupils listen and reflect on the lesson.

Learning Point: Consolidating lesson understanding

Continuous Assessment/Further Study

Type: Homework/Practice Exercise

Instruction: Answer the following questions and complete the drawing task:

1. List and briefly explain any four stages of the engineering design process.
2. Explain the difference between a plan and a front elevation in technical drawing.
3. Using appropriate drawing instruments, prepare the plan and front elevation of a simple object found at home (e.g., a matchbox, a small block of wood, a simple bottle). Ensure all necessary dimensions are included.

Lesson Keywords

• Engineering Design – A systematic process for creating or improving products, systems, or processes.
• Working Drawing – A detailed technical drawing providing all information needed for manufacturing or construction.
• Plan – The top view of an object in orthographic projection.
• Elevation – A view of an object from the front or side in orthographic projection.
• Orthographic Projection – A method of representing a 3D object in 2D by showing multiple views.
• Prototype – An early sample, model, or release of a product built to test a concept or process.

Differentiation

For students who grasp concepts quickly, encourage them to research advanced types of working drawings or design a more complex item. For students needing additional support, provide simpler models for drawing practice and offer one-on-one guidance during the practical session.

Suggested Lesson Videos

For further understanding, search on YouTube for:

• “Engineering design process explained”
• “Introduction to working drawings technical drawing”
• “Orthographic projection for beginners”