問31
頻出度★★☆
エンジニアリングシステムの CAM を活用する場面として, 適切なものはどれか。
平成23年度 特別試験 ITパスポート試験 問31
This question's explanation and your answers so far.
解説
問 31
Incorrectア
“Create design drawings for industrial products, buildings, and the like.” is a situation for utilizing CAD (Computer Aided Design). CAD is a tool for drawing the shape of a product or a building on screen and giving it dimensions in order to produce drawings or 3D models, and what it handles is design, an upstream process. CAM is the downstream mechanism that receives the data CAD has created and bridges it over to the machining side, so creating drawings itself is not the role of CAM.
- イ
正解 The correct answer is イ, “Output machining data for controlling machine tools.” CAM stands for Computer Aided Manufacturing, a mechanism that uses computers to support the manufacturing (machining) process. Specifically, it takes as input the product shape data and design data created with CAD, calculates along what path and how the tool should move in order to cut out that shape and at what feed rate and rotation speed the machining should be done, and then generates and outputs machining data (an NC program) that an NC machine tool or machining center can read directly. In other words, the role of CAM is to translate the designed shape into actual machine movements, turning it into data in a form that can control a machine tool, and the description in イ is exactly this function. An engineering system is a general term for the group of systems that use computers to support the work of technical departments such as design and manufacturing; it is enough to grasp the positioning that CAD handles design within that group, and CAM handles manufacturing downstream of it.
Incorrectウ
“Plan the order quantity of parts needed for product manufacturing.” belongs to the area of production control and materials management, typified by MRP (Material Requirements Planning). It is processing that calculates what should be ordered, when, and in what quantity from the production plan for the product, the bill of materials (BOM), and inventory levels, and what it deals with is planning information about quantities and timing. Its object and its purpose both differ from those of CAM, which creates machining data for driving machines.
Incorrectエ
“Formulate a monthly production schedule plan.” is a situation for the production planning and scheduling that a production control system is responsible for. It is planning work that allocates which products are to be made, when, and in what quantity over periods such as months, and its aim is to adjust the load and delivery dates of the factory as a whole. What CAM deals with is data for machine control, such as tool paths and machining conditions used when machining individual parts, so the work of drawing up production plans by period does not fall within the scope where CAM applies.
ここがポイント
- Distinguish the division of roles among CAD / CAM / CAE in engineering systems. CAD (Computer Aided Design) handles the creation of design drawings and 3D models, CAM (Computer Aided Manufacturing) handles generating machining data (NC programs) based on CAD data and controlling machine tools, and CAE (Computer Aided Engineering) handles analysis and simulation of strength, heat, and the like. Furthermore, the idea of integrating these together with production control so that the whole factory is handled by computer in a unified way is CIM (Computer Integrated Manufacturing).
- Even when both are aimed at manufacturing, engineering systems (CAD / CAM) and production control systems (MRP and production scheduling) cover different territory. The former deals with technical information such as the shape of an object and how it is machined, while the latter deals with planning information about quantity and timing, namely what to make or order, when, and how many. Judge by matching them up: if a choice is about drawings it is CAD, about machining data for a machine it is CAM, about order quantities it is MRP, and about schedule plans it is production planning.
用語