Manufacturing Processes and Production Systems: A Comprehensive Guide
Product Variety and Production Quantity
Relationship in Typical Factories
Production quantity and product variety generally have an inverse relationship. Factories producing a wide variety of products tend to have lower quantities for each product, while those specializing in a single product often have higher production volumes.
Manufacturing Capability
Manufacturing capability encompasses the technical and physical limitations of a manufacturing company and its individual plants. The text highlights three key categories:
- Technological processing capability
- Physical size and weight limitations
- Production capacity
Batch Production
Advantages for Medium Quantity Production
Batch production involves processing groups or batches of materials or parts together through various manufacturing operations. All units within a batch undergo processing at each station before moving on to the next. This method is often preferred for medium or low quantity production due to its efficiency. When the same machines are used for multiple product types, changeovers are necessary. Batch production helps distribute changeover time across a larger number of parts, reducing the average operation time per part.
Process Layout vs. Product Layout
Production Facility Configurations
Process layouts arrange machinery based on the type of process it performs. Products move through different departments in the order of required operations, often resulting in longer travel distances within the plant. This layout is suitable for high product variety and dissimilar operation sequences. In contrast, product layouts arrange machinery according to the general flow of products. This minimizes travel distance as products move sequentially through the production line. Product layouts are ideal when products follow a similar production sequence.
High Volume Production and Layout Types
High-volume production of assembled products is most closely associated with product layouts. This layout type optimizes efficiency for large quantities of standardized products.
Plant Capacity
Plant capacity refers to the maximum production rate a factory can achieve under specific conditions, including labor, operating hours, and other operational factors. This statement is true.
Batch Production Features
The following features and terms are associated with batch production:
- Medium quantity production
- Setup time between batches as a disadvantage
Tensile Strength and Yield Strength
Material Properties
Tensile strength is the maximum load a material can withstand during a tensile test, divided by its original cross-sectional area. Yield strength is the stress at which a material begins to deform plastically, often measured using the 0.2% offset method.
Hardness Testing
Hardness measures a material’s resistance to indentation. It is typically tested by pressing a hard object (e.g., sphere or diamond point) into the material and measuring the size of the indentation.
Rotational vs. Prismatic Parts
Machining Considerations
Rotational parts have cylindrical or disk shapes and are machined using turning machines like lathes. Prismatic parts are block-shaped or flat and are usually produced on milling machines, shapers, or planers.
Workholding in a Lathe
Various methods are used to hold workpieces in a lathe, including:
- Between centers
- Chuck
- Collet
- Face plate
Apron Movement in an Engine Lathe
The apron in an engine lathe can be moved using two mechanisms:
- Lead screw: Provides rapid advancement for cutting threads and quick tool movement with precise feed control.
- Feed rod: Enables slow forward movement for most turning operations.
Turret Lathe vs. Engine Lathe
A turret lathe features a toolholding turret instead of a tailstock, allowing multiple cutting operations without the need for tool changes as in a conventional engine lathe.
Lathe Operations and Tool Feeding
Three common lathe operations and their tool feeding methods include:
- Straight turning: Tool fed parallel to the workpiece’s axis of rotation.
- Taper turning: Tool fed at an angle to the workpiece’s axis of rotation.
- Contour turning: Tool follows a non-straight contour.
- Cut-off (parting): Tool fed radially into the rotating workpiece.
Threading vs. Tapping
Threading creates external threads on a turning machine, while tapping produces internal threads, typically using a drilling machine.
Drilling Force and Torque
Force and torque in drilling may increase slightly with hole depth due to factors like increased contact area and chip removal challenges. However, unless the hole is very deep, these factors are generally considered negligible.
Speed and Feed Adjustments in Drilling
Speeds and feeds should be reduced as hole depth increases to mitigate stresses on the drill caused by elastic recovery in the workpiece. Higher stresses can increase torque and potentially lead to drill failure.