Introduction to Mechanical Drawing

 

Here,As an introduction to mechanical drafting drawings, "Thoroughly explains everything from basic rules to how to draw."　I would like to leave a note that

 

We are sure that you have had the experience of wondering, "Will this really convey the message?　　Especially for beginners, there are many basics and company rules to learn, and it may be difficult to know where to start.　Some of you may even feel a sense of frustration at the decrease in the number of people who can do drafting.

 

Mechanical drafting is more than just drawing shapes,Language to accurately convey the designer's intent to the manufacturing floor　It is.　Therefore, it is essential to master the correct way of drawing.　This article covers the basics about mechanical drafting drawings, the rules that conform to JIS standards, specific drawing methods, and the types of drawings you should know,Comprehensive explanationI will do so.

Understand the basics in mechanical drafting drawings

Outline of JIS standards, the constitution of drafting

The most important thing in mechanical drawing is to follow the common rules that have been established.　JIS (Japanese Industrial Standards) is the foundation of these rules.

 

JIS is a national standard that defines standards and measurement methods for Japanese industrial products, and the main principle in mechanical drafting is to create drawings in accordance with JIS.　This allows the designer to communicate information to the manufacturer in a uniform manner that can be interpreted the same way by anyone who sees it.

 

Among the JIS related to mechanical drawing, the first one to be pressed is "JIS B 0001: Mechanical Drawing".　This standard sets forth comprehensive rules for the creation of parts and assembly drawings, and can be considered the bible of mechanical drafting. Furthermore, this "JIS B 0001" is also based on a larger standard, "JIS Z 8310: General rules for drafting," which defines the basic principles for all types of drafting.

 

In addition, these standards are not fixed, but are revised in response to technological advances and internationalization trends.　In recent years, there has been an active movement toward greater consistency with ISO, the international standard.　In particular, the concept of "GPS (Geometric Property Specification of Products)," which defines the shape of a product using globally common rules, has been introduced, and JIS has been updated to conform to this concept. In this day and age, global manufacturing has become the norm,The ability to create drawings with an awareness of international standards is an essential skill for designers.　I am sure you will.

 

 

Title column and scale to determine drawing style

A drawing is complete only when there is not only a drawn figure but also a variety of information that complements it.　The title column is one of the most important parts of the drawing. Among these, the title column is the "identification" of the drawing.

 

Creation rules for each size in the figure frame as well.　The title column is usually located in the lower right corner of the drawing and contains important information about the drawing.　It includes the drawing number, drawing name (part name), company name, and a signature line that identifies responsibilities such as design, drawing inspection, and approval.　In addition, the basic rules for reading the drawing, such as scale and projection, which will be discussed later, will be clearly stated.　If this information is not accurate, the drawing will not be accepted as official.

 

The next important factor is scale.The scale indicates the ratio between the size of the figure on the drawing and the actual size of the product　In,Drawing scale recommended by JIS　There are

• When drawing at the same size as the real object at the present scale: 1:1
• Scale: When drawing smaller than the actual size, such as 1:2 or 1:5
• Double scale: When drawing larger than the actual size, such as 2:1 or 5:1.

Which scale to use should be chosen based on the size of the product and the size of the paper, and the one that most clearly represents the figure.　　However, there is one rule that must never be forgotten here.　That is, the dimensional values to be entered in the drawing should always be the "actual finished dimensions," no matter what scale they are drawn in.　Failure to adhere to this principle can lead to fatal errors on the manufacturing floor.

 

 

The use of line types, which are types of lines that have meaning

Mechanical drawings use different types of lines to represent complex shapes and information.　Line type (line type) and thickness are strictly defined by JIS, and each serves as a "character" with a specific meaning.

 

The main line types that beginners should learn first are as follows

Name of line	appearance	Main applications
outline	thick solid line	This is the most basic line in a drawing that outlines the visible portion of a part.
hidden line	dotted line	Shows the shape of areas that are not directly visible from the current viewpoint. Care should be taken because excessive use can complicate the drawing.
center line	thin, single-pointed line	Indicates the center of a circular hole or cylindrical shape, or the central axis of a symmetrical figure.
dimension line	thin solid line	Arrows, etc., are attached to both ends to indicate dimensions.
dimensioning aid	thin solid line	This is an auxiliary line to draw from the figure to the dimension line.
disconnection line	Thin single-pointed line (thicker at both ends)	It is used to show where the section was cut when creating a cross-sectional drawing.

If these lines overlap in the same location, a priority order is defined for the lines that appear.In general, the order of priority is "outline lines > hide lines > cut lines > center lines," and rules are established so that more important information is not hidden.　The company has been

 

There is also a rule for line thickness, generally a 2:1 ratio of thick to thin lines.　This contrast in thickness increases the visibility of the drawing and allows the viewer to intuitively understand where the outline of the part is and where the auxiliary lines are.

 

Also,Characters used in mechanical drawing　It is also a good idea to check the rules regarding

 

 

The projection method to convey shape and the Japanese third angle method

The projection method is used to accurately represent three-dimensional parts on paper or screen, which is a two-dimensional plane.　In mechanical drafting, three-dimensional shapes are communicated by combining diagrams viewed from multiple directions.

 

The standard method used in Japan, the U.S., and other countries is the third angle method.　The third angle method is based on the idea that the object is placed inside a transparent box and the shape seen from the outside of the box is projected onto the front side.

 

Following this rule, the placement of each drawing is determined as follows

• Front view: The figure representing the most characteristic shape of the object is placed in the center.
• Plan view: The top view of the front elevation, placed directly above the front elevation.
• Right side view: Viewed from the right, the front view is placed directly to the right of the front view.

This placement relationship is an absolute rule, and it is this regularity that allows us to accurately reconstruct a three-dimensional shape in our minds from a two-dimensional drawing.

 

On the other hand,In Europe and elsewhere, a different placement rule called the first angle method is used.　The first angle method is based on the concept of projecting the object onto the other side of the object, so the arrangement is opposite to the third angle method, for example, the right side view is placed to the left of the front view.　The interpretation of the shape is completely different depending on which projection method is used to draw it,The title column of the drawing must always include a symbol indicating which projection method was used.

 

 

Cross-sectional view showing interior and hatching basics

When there are complex shapes inside a part, it becomes difficult to accurately convey the shape using only hide lines.　　Cross-sectional views are very effective in such situations.

 

Cross-sectional drawing is a drawing method used to cut a part in a virtual plane and show its cut edges in order to clearly show internal shapes that are not normally visible. The cut section is drawn as an outline line (thick solid line), so the shape can be understood much more clearly than if it were drawn as a hide line.

 

There are several types of cross sections.

• Full sectional view: This is the most common sectional view, showing the entire part completely cut away.
• One-sided cross-sectional view: For a symmetrical part, one half of the part is shown as an external shape and the other half as a cross-sectional shape with the center line as the border. Both the inside and outside shapes can be shown at the same time.
• Partial section: A diagrammatic method in which only a portion of a part is torn out to show only the interior of the required part.

In cross-sectional views, a diagonal line, called hatching, is applied to clarify the cut surfaces.Hatching is usually drawn with thin solid 45-degree lines, and when multiple parts are adjacent to each other, such as in an assembly drawing, each part can be distinguished by changing the direction and spacing of the lines.　I will do so.

 

However, there is an important exception rule for cross sections.In principle, parts such as shafts, bolts, nuts, pins, gear teeth, and ribs should be drawn in outline, not in section, even if a cut line passes through them, because cutting in the longitudinal direction does not provide new information or makes the drawing more difficult to understand.　It is.　　It is also important to understand this rule in order to create a correct cross-sectional drawing.

 

 

Correct mechanical drafting drawing rules

How to choose the most important front view

When creating a projection drawing, which view to choose as the "front view" is an extremely important decision that affects the overall clarity of the drawing. The front view is the center of information about the part, so it must be chosen carefully.

 

The principles for selecting the front view are as follows

• Choose the orientation that best conveys the shape and function: The first principle is to choose a front view that most clearly conveys the most distinctive shape of the part and its function when used as a product. For example, if a disc-shaped part has multiple mounting holes, the front view should be the side that shows the arrangement of the holes.
• Minimize the use of hide lines as much as possible: As mentioned above, hide lines (dashed lines) complicate drawings and can lead to misunderstandings. Therefore, it is recommended that the front view be selected in an orientation that minimizes the use of hidden lines, such as when internal geometry is visible.
• Consider the posture of the part when machining: Ease of operation on the manufacturing floor is also an important consideration. If possible, draw a front view of the part in a stable position when it is placed on the machine and in the orientation in which the main machining operations are performed, so that the machinist can easily compare the drawing with the actual part.

These principles are not mere rules, but rather a way to communicate the designer's intent more clearly and efficiently. An improper front view can confuse the person reading the drawing and increase the risk of manufacturing errors. The choice of which orientation to use for the front view is itself a design skill.

 

 

Dimensions and tolerances to allow for variations in fabrication

It is practically impossible to manufacture a part exactly to the dimensions shown on the drawing without any deviations.　It is.　No matter how precise the processing machine is, there will always be slight errors (variations). Tolerance is set to allow for this inevitable variation within a range that does not impair the function of the product.

 

The dimensions themselves are also optional in how they are put in and displayed.　The dimensional tolerance indicates the maximum allowable error with respect to a standard dimension.　The dimensional tolerance indicates how much error is allowed with respect to a standard dimension, and is expressed as "50±0.1".　In this case, if the finished dimension is within the range of 49.9mm to 50.1mm, it is acceptable.

 

Because specifying individual tolerances for all dimensions would make drawings very complex, it is common practice to use thenormal mode tolerance　The concept of "default tolerance" is used.　This is the "default tolerance," so to speak, that is applied to dimensions for which no individual tolerance is specified.　　By specifying a grade such as "JIS B 0405-m (m means intermediate)" in a note column of a drawing, the accuracy level of the entire drawing can be indicated collectively.

 

When filling in dimensions, the main principle is to avoid duplicate dimensions　There are　For example, if you provide both the overall length dimension of the part and the dimensions of each part that comprise it, the tolerances of each may interfere with each other, creating manufacturing inconsistencies.　If the dimensions are to be given as a reference, the values should be enclosed in parentheses ( ) to make it clear that they are not the dimensions to be controlled.

 

that the tolerances be set appropriately.Tolerance design　It is called "tolerance" and is essential for assuring product quality, and at the same time, it is directly related to cost control.　Unnecessarily tight tolerances can increase machining costs, so designers must be able to determine the appropriate tolerance for the function of the part.

 

 

Fits that determine the mating accuracy of parts

In mechanical products that combine multiple parts, the accuracy of the part where two parts fit together, such as a hole and a shaft, is particularly important. The tolerance system used to control the accuracy of this fit is fitting.

 

There are three main types of mating.

• Clearance fit: A fit in which the hole dimension is always larger than the shaft dimension, creating a clearance between the two. This type of fit is used for parts that involve movement, such as a shaft rotating in a bearing.
• Clamping fit: A fit in which the shaft dimension is always larger than the hole dimension and pressure must be applied when assembling. This type of fit is used when you want to firmly secure a part, such as in a press fit.
• Intermediate fit: A fit in which variations in the dimensions of the hole and shaft can result in a small clearance or interference. Used for positioning pins that require disassembly and assembly.

These relationships are indicated by a combination of letters and numbers (e.g., H7, g6) as specified in JIS B 0401. Upper case alphabets indicate hole tolerances and lower case letters indicate shaft tolerances.

 

In actual design, the dimensional tolerance of the hole is fixed to a standard (e.g., H7), and the tolerance of the shaft (e.g., g6 easy fit, p6 or tight fit) is selected according to the type of fit desired.The "hole standard fitting method" is generally adopted.　This is the case for all the products. This is,To standardize the types of tools (e.g., reamers) used to precisely machine holes, which is advantageous in terms of cost　It is.

 

Setting the proper fit is an important factor in determining whether a machine will run smoothly or whether parts will be securely fastened.

 

 

Geometric tolerances to precisely dictate shape

Dimensional tolerances regulate the variation in the "size" of a part, but they alone cannot guarantee the "shape" of the part itself.　　For example, even if the thickness of a board is within dimensional tolerances in any part measured, the entire board may be significantly warped.　　SuchThe shape distortion is used to regulate theGeometric Tolerance　It is.

 

Geometric tolerancing, also called GD&T (Geometric Dimensioning and Tolerancing), is a language used to indicate how geometrically correct a part's shape is (e.g., how straight, flat, or circular). The symbols defined by JIS are classified as shown in the table below.

category	special characteristic	symbol	datum requirement	Brief Description
Shape Tolerance (Single Shape)	straightness	—	unnecessary	How straight is the line element?
	levelness	⏥	unnecessary	How flat the surface is.
	circularity	○	unnecessary	How close the circular form is to a perfect circle.
	cylindricity	⌭	unnecessary	How close the cylindrical form is to a perfect cylinder (regulating roundness, straightness, and taper).
cylindricity	Line Contour	⌒	depend (on the situation)	Regulates the two-dimensional contour shape of complex curves.
	Surface Contour	⌓	depend (on the situation)	Regulates the 3D contour shape of complex curved surfaces.
Attitude tolerance	parallelism	//	necessary	How parallel a given form is to the datum.
	right angle	⊥	necessary	How perpendicular (90°) an object is to the datum.
	gradient	∠	necessary	How accurately a given form maintains a specified angle to the datum.
Position Tolerance	location	⌖	necessary	Regulates the position of holes and other forms relative to the datum.
	coaxiality	◎	necessary	How much the two cylindrical forms share a common axis.
	concentricity	◎	necessary	How well the center points of the circular shapes coincide. (Coaxiality is often recommended.)
	symmetry (physics)	⌯	necessary	How symmetrical is a given form with respect to the datum center plane?
Runout Tolerance	circumferential vibration	Right up arrow	necessary	Regulates errors in shape and position in each circumferential section when rotating parts.
	general shake-out	⌰	necessary	Simultaneously regulates shape and position errors across the entire surface when rotating parts.

Appropriate use of these geometric tolerances makes it possible to communicate more detailed and precise design intent to the manufacturing site, which cannot be conveyed by dimensional tolerances alone.　　Particularly in products where multiple parts are precisely assembled, shape control through geometric tolerancing is essential to assure quality.

 

 

Role of datum as a reference for geometric tolerances

As mentioned above, some geometric tolerances, such as "posture tolerance" and "position tolerance," regulate the relationship with something else.　For example, when indicating "parallelism," it is meaningless without a standard of "parallelism to what?　ThisA reference, theoretically exact point, line, or plane is called a datum.

 

Datum, so to speak, represents the "starting point" for measurement and processing　is.　On a drawing, it is indicated by enclosing a capital letter of the alphabet (A, B, C, etc.) in a square and directing it to a reference surface or line with a triangular symbol.

 

For example, when instructing "parallelism 0.05" for a surface, the reference surface is first set as "datum A".　This conveys the clear requirement that "the indicated surface must fit between two parallel planes with a width of 0.05 mm relative to datum A.

 

For complex parts, a "datum system" may be constructed by setting up three planes (datum A, B, C) that are orthogonal to each other.　　This completely constrains the position and orientation of the part in 3D space and allows for more exact positional relationships to be defined.

 

Setting and directing datum correctly is a prerequisite for the effective functioning of geometric tolerancing.An important role in conveying the design concept itself, which aspects the designer considers the accuracy of a part based on.　The company is responsible for

 

 

Surface roughness indicating smoothness of finish

The "finish" of a part's surface, how smooth or rough it is, is also an important factor that greatly affects the performance of the product.　The following is a list of the most common problems that can occur.　　For example, a rough finish on surfaces where parts slide against each other or seal with O-rings, etc., can cause premature wear and fluid leakage. Surface properties, generally called surface roughness, indicate the degree of finish on these surfaces.

 

On the drawing, a symbol similar to a check mark is used to indicate the surface to be controlled.　Then, parameters and numerical values are appended to the symbols to define the specific level of smoothness.

 

The most commonly used parameter is "Ra" (arithmetic mean roughness).　This is the value obtained by averaging the measured surface irregularities and indicates the general smoothness of the entire surface.　The unit is micrometer (µm). The smaller the number, the smoother the surface.

 

Another commonly used measure is Rz (maximum height roughness).　This indicates the difference in height between the top of the highest mountain and the bottom of the deepest valley within the measurement range.　This parameter is effective for quality control of sealing surfaces, where even a single deep scratch on the surface can cause problems.

 

How much surface roughness is required depends on the function and role of the part, but it isProcessing to realize　It is.　　A rough finish is sufficient for internal parts that do not affect appearance, but a smooth finish (small Ra value) is required for high-precision sliding parts and exterior parts that must have a pleasing appearance.　This also,Need to give appropriate instructions considering the balance between quality and processing cost　There are

 

 

Dimension aid symbols to assist in dimension entry

When entering dimensions, dimensional auxiliary symbols are used to express information about shapes that cannot be conveyed by numerical values alone in a concise and clear manner. These symbols are defined by JIS, and their correct use makes drawings much easier to understand.

 

Typical dimensional auxiliary symbols that beginners should learn first include the following

• φ (phi): Indicates the diameter of a circle. For example, "φ20" means that it is a circle or cylinder with a diameter of 20 mm.
• R (radius): Indicates the radius of a circular arc. R5" indicates a rounded corner with a radius of 5 mm, for example.
• C (C): Indicates a chamfer that is primarily 45 degrees. A "C3" indicates a chamfer with a 45-degree angle and a width of 3 mm; chamfers other than 45 degrees must be specified separately for angle and dimension.
• Sφ: Indicates the diameter of the sphere.
• t (t): Indicates the thickness of the board. It is useful for specifying the thickness of a board, for example, "t=2".
• □ (Square): Indicates the length of the sides of a square. □40" means that each side is 40 mm square.

 

By prefixing these symbols with dimensional values, information about the shape can be accurately conveyed without spending many words.　For example, simply writing "20" does not tell whether it is a width or a diameter, but writing "φ20" unambiguously conveys that it is a cylindrical shape.　Dimension Auxiliary Symbols are a powerful tool for making drawings concise and clear.

 

In addition to the aforementioned "normal tolerance", especially in the part drawing, "normal tolerance" can also be used.Corner without indication shall be thread chamferedThere are also such things as comprehensive notes, such as "I have a new name for you," etc.Mechanical drawings can be made to clearly indicate where instructions are given and where they are not, and to make the content clear and crisp, so that the content can be easily conveyed.

 

 

Types and roles of drawings handled in mechanical drafting

Parts and assembly drawings as the core of manufacturing

The most basic and important drawings in mechanical design are "parts drawings" and "assembly drawings," and JIS B 0001 (Mechanical Drawing) also mainly specifies these drawings.

 

Part Drawing

A parts drawing contains all the information necessary to produce a "single part that cannot be disassembled any further".　It is.　The workers on the manufacturing floor rely solely on these drawings to fabricate the part.　Therefore, it contains all the information needed to create a single part, including a projection that completely defines the shape of the part, all dimensions and tolerances, necessary geometric tolerances, materials, heat treatment, surface roughness, and more.

 

How to draw a parts diagram　It is no exaggeration to say that the quality, cost, and delivery time of a product are directly related to the quality, cost, and delivery time of a welded product.　　Other drawings for welded products includewelding symbol　It will also be necessary to state the

 

Assembly Drawing

Assembly drawings show how multiple parts fit together to form a product or unit and their relative positions　It is.　　Assembly drawings are essential for understanding the overall structure of a product and for performing assembly operations.　Assembly drawings include "balloons," which are numbered to identify each part, and "balloons," which list the information on those parts.Parts Listwill be listed.

 

If a parts diagram is a dictionary that defines individual "words," an assembly diagram can be compared to a grammar book that uses those words to construct "sentences.Basic drawing style for assembly drawings as well.　There is a　They complement each other to bring a product to completion.　Assembly drawings may also describe assembly components for identification purposes, andIndication of steel materials used　and others to help you get a sense of the size, etc.

 

Planning and approval drawings linked to the design process

Each phase of design produces drawings with different objectives.

 

• Conceptual and planning drawings: These drawings are made at the earliest stage of design. They are used to establish the direction of the design by roughly depicting the basic structure, function, size, and arrangement of major purchased parts of the product. At this stage, technical issues and cost estimates are made.
• Production Drawing: This is a generic term that refers to a set of drawings required to actually manufacture a product. Generally, it includes the aforementioned parts and assembly drawings.
• Approval Drawings: After the design is completed, these drawings are submitted to the customer or related departments for confirmation and approval that the design conforms to the specifications. Usually, they mainly contain external dimensions, mounting dimensions, and information on interface areas, and are important documents for contractual purposes.

 

Material or layout drawings with a specific purpose

Sometimes more specialized drawings are used to convey specific information.

• Material drawing: A drawing used to define the shape of a material before machining, such as castings and forgings. It is used to place an order with the material manufacturer.
• Layout drawing: A drawing that shows how an entire machine or device will be placed in a factory, building, or other installation location. It is used to check for interference with foundations and other equipment, and is important in plant design.
• Isometric (isometric projection) and exploded views: These diagrams are used to express the structure of a product in three dimensions in an intuitive and easy-to-understand manner. Exploded views show how parts are put together in an exploded view, and are especially useful in assembly instructions, service manuals, and presentation materials.
• revised map: These drawings are for revising and replacing drawings that have already been submitted.　This revised drawing contains historical information.
• Patent Drawings: Drawings showing the specifics of the patent for which the patent is being patented.

 

 

Schematics representing the logic of the system

Mechanical products often incorporate complex elements such as hydraulics, pneumatics, and electricity, and schematics are used to represent these functional connections.　Schematics are not the physical arrangement of components,The logical connection of how the system operates is shown using standardized symbols.

• Hydraulic and pneumatic schematics: Components such as pumps, valves, and cylinders (actuators) are represented using the graphical symbols specified in JIS B 0125. This shows how hydraulic oil and compressed air flow and how each piece of equipment is controlled.
• Electrical Circuit Diagrams: Represent electrical components such as power supplies, switches, relays, motors, sensors, etc., using the graphical symbols specified in JIS C 0617. It shows electrical connections between components and clarifies control logic and sequences.

 

Drawing knowledge of mechanical drawing useful in practice

Materials and heat treatment determine component performance

In addition to the shape and dimensions of the part, what it is made from, or "material," is also important information that should be indicated on the drawing.　The choice of material determines the performance of the product itself, including its strength, durability, weight, corrosion resistance, and cost.

 

Materials are accurately specified in the title column or parts list using the material symbols specified by JIS. For example, the following symbols are commonly used.

Material Category	JIS symbol (example)	generic name	Main Features and Applications
carbon steel	S45C	medium-carbon steel	It has a good balance of strength and workability and is widely used for shafts and gears.
stainless steel	SUS304	18-8 stainless steel	It has excellent corrosion resistance and is used in food machinery and chemical plant equipment.
aluminum alloy	A5052	Aluminum-Magnesium Alloy	Lightweight and corrosion resistant, it is used for general sheet metal parts.

In addition, heat treatment is sometimes used to maximize the performance of a material.　Heat treatment is a technique for heating and cooling metals to change their structure and improve mechanical properties such as hardness and tenacity.

 

Typical heat treatments include

• Quenching: A process in which steel is heated to a high temperature and then quenched in water or oil to obtain an extremely hard structure.
• Tempering: Tempered steel is hard but brittle, so it is heated again at a lower temperature than at the time of quenching to restore its tenacity (toughness). Normally, quenching and tempering are performed as a set.

These heat treatment instructions also,Specifically describe the type of treatment and the required hardness as a note on the drawing, such as "induction hardening HRC 55-60".The following is a brief overview of the process.　Proper material selection and heat treatment instructions are fundamental to satisfying the required functionality of the part.

 

 

Processing instructions for ease of manufacturing

A good drawing is one that not only accurately depicts the designer's requirements, but also takes care to ensure that the part can be manufactured efficiently and economically.　This consideration of "ease of manufacture" from the design stage is called DFM (Design for Manufacturability).

 

Design that ignores the conditions of the machining shop floor can lead to unnecessary cost increases, delivery delays, or "unprocessable" situations.　For example, the following points should be noted in the cutting process

• Avoid sharp inside corners: Because the end mill, a cutting tool, is machined while rotating, the inside corners of the shape will be rounded (R) by the radius of the tool. Directing a right-angled pin angle requires special machining and increases cost. Whenever possible, it is wise to provide an R on the inside corner or create what is called a "relief" shape on the corner.
• Avoid holes or grooves that are too deep: If the hole depth is extremely large in relation to the diameter, it may require a long special drill or cause chips to be improperly ejected, resulting in reduced machining accuracy.
• Avoid walls that are too thin: If the wall thickness is too thin, the part is more likely to deform (chatter) due to force or heat during processing, making it difficult to achieve dimensional accuracy.

It is important for designers to imagine what tools and processes will be used to shape the lines they draw on site.　　If possible, by interacting with the actual fabricators,To be told about the actual processing that I didn't know about.　There are also

 

If it is difficult to have such a conversation with the field, at a minimumBasic knowledge of cutting operations.　This makes it easier to create more realistic and manufacturer-friendly drawings.　　It also helps to ensure that the products being made areChange the drawing expression depending on whether it is a prototype drawing or a drawing of a mass-produced part.　is a good idea.

 

 

What is the final process drawing to prevent mistakes?

Once the drawings are completed, they are not immediately handed over to the manufacturing site.　An extremely important process, called drawing inspection, awaits to ensure that there are no design errors or omissions.Inspection drawings are the last resort to assure design quality and prevent rework and problems in later processes.

 

Generally, drawing inspections begin with a self-check by the designer himself/herself, followed by a check by a third party such as a colleague or supervisor.　By checking from multiple perspectives, it is easier to detect errors and oversights caused by assumptions.At a minimum, it is effective to use the following checklist to systematically check the drawing　It is.

 

 

Forms and Standards

• Is the title column complete and correct (figure name, figure number, material, scale, etc.)?
• Are the symbols for the projection method (third angle method) listed?
• Are the line type and thickness correct according to JIS?
• Are all views correctly aligned?

Geometric Definition

• Are the parts completely dimensionally defined (can the manufacturer make them without questions, no dimensional omissions)?
• Are there any overlapping dimensions?
• Is the choice of frontal view logical?
• Are cross sections and details used correctly and clearly?

Tolerance and Function

• Are tolerances specified for all critical dimensions?
• Are normal tolerances noted?
• Is the dimensioning method (series/parallel) functionally appropriate considering the accumulation of tolerances?
• Are fit tolerances (e.g., H7/g6) correct for the application?
• Are GD&Ts used where necessary to manage shape, orientation, and position, and are datums clearly defined?

Manufacturability and Assemblability

• Does the design consider standard tool sizes (drill diameter, corner R, etc.)?
• Are there any shapes that are impossible or unnecessarily difficult to machine (deep pockets, sharp internal angles, etc.)?
• Does this part fit together correctly with the mating part (check the assembly drawing)?
• Is there room for tools during assembly (can bolts be tightened with a wrench?)

 

A single mistake can lead to significant financial losses and delays in delivery.　Inspection drawings other than the company's own.Practitioner's Inspection Drawing　andAdministrator's Inspection Drawing　Learn how it is done separately, etc,To perform drawing inspections specific to your company.　is the key point.

 

 

CAD and 3DA/MBD essential for modern drafting

Most drafting work that was once done by hand is now done by computer-aided design (CAD) systems.　The widespread use of 3D CAD, in particular, has revolutionized the design process.

 

In a typical modern workflow, a three-dimensional part model is first created using 3D CAD, and then a 2D drawing is created from the 3D model in the form of automatically generated projection drawings.　This method has many advantages, such as preventing omissions of corrections, improving drafting efficiency, and facilitating shape understanding.

 

In recent years, the concept of MBD (Model Based Definition), in which all manufacturing information (PMI) such as dimensions, tolerances, and notes are added to the 3D model itself, eliminating the need for 2D drawings itself, has also been gaining popularity.　By using the 3D model as the sole source of information, this approach aims to prevent double management of information and further improve efficiency by linking all processes, from design to manufacturing and inspection, with digital data.

 

In this context, the technique of embedding PMI into a 3D model is called 3DA (3D annotation).

 

 

The Future of Drawingless and Mechanical Drafting Drawings

Current Status and Challenges of Drawing-less System in Manufacturing Industry

The aforementioned MBD concept is,This has led to a major trend toward "drawing-less" production in the manufacturing industry.By consolidating all information into a 3D model and passing the data to subsequent processes as positive, it is expected to reduce the cost of creating and managing 2D drawings and improve the accuracy and speed of information transfer.

 

However,This drawing-less approach has not been ideal.　In particular, the following challenges and harms have been identified

• Slow penetration among SMEs: Operating MBD requires expensive software, viewing terminals, and training to master them. For many SMEs in the supply chain, this investment is a significant burden, resulting in a digital divide between the source and destination of orders.
• Quality Assurance and Inspection Challenges: Traditional 2D drawings have been the "contract" for quality assurance with dimensions and tolerances; 3D model-based inspections are possible, but 2D drawings are still often required as the basis for final pass/fail decisions and as evidence of inspection records. The 3D model is a good starting point for the inspection of a building.
• Emergency and on-site responsiveness: When unexpected problems occur at the manufacturing site, paper drawings are extremely effective because everyone can refer to them immediately. In addition to being able to check information even in the event of a network failure or power outage, paper drawings are intuitive and excellent for discussions among the parties involved as they are written.
• Loss of Know-How: The act of drawing is not just a task. It is a process in which designers think deeply about the functions and processing methods of parts and condense their intentions. There is a concern that an excessive shift to drawing-less design will simplify this thinking process and make it difficult to develop young designers.

 

Also,The skill and necessity of hand-drawn drawings　Drawing and drafting skills will continue to be essential in light of the

 

 

Why are drawing skills still important today?

suchEven in the midst of the trend toward drawing-less design, the skill to create mechanical drafting drawings remains, and will continue to remain, essential for designers.　The reasons for this are manifold.

 

First, because drawings lay the foundation for design thinking.　Training in drawing from scratch according to JIS standards is one of the most effective ways to learn to systematically understand the concepts that form the foundation of machine design, such as projection methods, tolerancing, and machining methods.Without this basic strength, it is not possible to add appropriate information to the 3D model.

 

Second, because drawings are a universal communication tool.　　As mentioned above,Not all of our suppliers have the latest 3D equipment.2D drawings still serve as a reliable means of communicating information that is not easily affected by the size of a company or its IT environment.　Especially when considering issues such as data compatibility between different CAD systems,PDF-enabled 2D drawings remain highly reliable.

 

And third,Drawings are official documents that record the "intent" and "responsibility" of the design　That is why.　　Every single dimension and tolerance is engraved with the designer's thought process.This condensed information is an important complement to the 3D model in verifying problems as they occur and in reviewing past design assets.

 

Ultimately, 3D models and 2D drawings are not opposites, but rather complementary to each other.　Whereas the 3D model indicates "what" is to be made, the 2D drawing logically defines "how" and "to what standard" it is to be made.The ability to master both is the skill required of today's and tomorrow's designers.I believe it is.

 

For that reason,Textbooks on Mechanical Drawing　I work hard every day on my drafting work with the

 

 

For correct mechanical drafting drawings

Throughout this article, we have provided a comprehensive overview of the basic concepts, specific rules, and practical knowledge for creating mechanical drafting drawings. Finally, the main points for creating accurate and easy-to-understand drawings, as well as the mentality of theDraftsman Awareness　I will conclude by introducing an important way of looking at drafting.

 

• JIS standards are the absolute rulebook for drawing creation
• Drawings are composed of basic elements such as projection, linetype, and scale
• The choice of front view determines the overall clarity of the drawing.
• Cross-sectional views are an effective means of clearly communicating internal geometry
• Dimensions and tolerances are critical information that affect product quality and cost
• Mating is a system that controls the accuracy of mating between parts
• Geometric tolerances dictate accuracy of geometry that cannot be shown by dimensional tolerances
• Datum is the basis for applying geometric tolerances
• Surface roughness dictates the degree of finish according to the function of the part.
• Dimension Auxiliary Symbols Make Drawings Concise and Clear
• Materials and heat treatment determine component performance
• Design for ease of machining improves cost and delivery time
• Drawings are the last stronghold to eliminate errors and guarantee quality.
• Use different types of drawings for different purposes, such as parts drawings, assembly drawings, schematics, etc.
• Even in today's drawing-less world, basic drawing skills are fundamental for designers.

 

That's it.