Rapid Prototyping in Mechanical Engineering - Definition, Types & Applications
WHAT IS PROTOTYPE ?
A prototype is an approximation of a product or system or its components in some form for a definite purpose in its implementation.
A prototype is a vital part of the product development process. In design practice the word prototype is not limited to a physical object only. It can also be used as a verb or an adjective depending on the contact. Prototypes means - A verb to produce a design & An adjective (prototype like PCB).
WHAT IS PROTOTYPING?
Prototyping is the process of creating prototypes of a product or system in order to test analyze the design before final manufacturing. Prototyping is the process of developing an initial model of a product to check its performance, design & functionality.
THREE ASPECTS OF A PROTOTYPE
Implementation of prototype :
This refers to whether the prototype represents the complete product or only a part, sub assembly or component.
A complete prototype models most of the product's characteristics and is usually full scale & fully functional.
It may be tested by focus groups to identify problems before final design.
Form of prototype:
This describes whether the prototype is virtual or physical.
Virtual prototypes are non tangible & exist as mathematical models or computer simulations.
These are used when physical models are too costly or time consuming Limitations:-Depends on current specific understanding.
Couldn't predict unexpected problems.
Degree of approximation:
This indicates how closely the prototype resembles the final product. It can range from a very rough representation to an exact replication.
ROLE OF PROTOTYPE
Prototypes is not a just products model but also guide full design process and They are -
Experimentation & learning
Testing & proofing
Communication and interaction
Synthesis & integration
Scheduling & makers
1. Experimentation & Learning:
It is a first role of prototype in which Try ideas in piratically, learn form creating design & understanding about real fuel.
Allowing designers to understand the practical behavior of the product.
2. Testing & proofing:
A tool that is used to test prototyping including checking concepts did really work?
At an early stage design flaws were caught.
In this, they are used for testing & proofing concepts to check whether ideas work as intended.
3. Communication & interaction:
Prototype is a powerful communication tool between designers, managers & customers.
Overall prototypes improve communication among the development team, management & customers for providing a physical model that offers better visuals and tactile understanding than sketches.
4. Synthesis and integration:
Testing of all components after integration where checking all parts are working or not, finding assembly problems and understanding manufacturing issues.
By combining various components to ensure proper functioning and to identify manufacturing and assembly issues.
5. Scheduling & markers:
It defines a project phase in which every prototype is a milestone. This milestone gives a lesson which phase is completed and also Management decision depends on prototype.
It indicates the completion of different phases of development and helping management decide whether to continue the project.
WHAT IS RAPID PROTOTYPING ?
Rapid prototyping is an additive manufacturing process that creates objects directly from a 3D CAD model by building it layer by layer . It doesn't require a traditional tool , model or machining operation.
In rapid prototyping CAD models are first sliced into layers and then the machine generates the real object by adding material sequentially to those layers.
Rapid prototype has two kind of outputs:
Direct prototype
Indirect prototypes
Direct prototype
These are the parts that are produced directly by rapid prototype machines and can be used immediately as prototypes without any additional processing. These prototypes are usually made from non – metallic materials but are accurate and detailed.
They are mainly used for Visual evaluation, Shape and form assessment, Ergonomics studies & Design verification.
Indirect prototypes
In this case the rapid prototype produced part is not the final prototype, but it is used to make molds or patterns , which are then used to cost the actual prototype component.
This method is used because most commercial rapid prototype machines work with non – metallic, low– strength, low temperature material so they cannot directly produce strong metallic prototypes. Therefore rapid prototypes act as a Pattern, Master models, Mould inserts.
Working steps of rapid prototype :
Step 1: CAD model creation (virtual level) :
A 3D model of the component is created on a CAD system.This model contains the exact shape & diamentions of the part.
Step 2: Slicing CAD models :
The CAD model is divided into a series of thin horizontal layers. Each layers represents a thin cross – section of the final object. The slice thickness corresponds to the layer thickness that the rapid prototype machine generates.
Step 3: Layer – by – Layer generation :
The rapid prototype machine creates the physical object by adding material layer by layer following the sliced data. Each layer is placed on top of the previous one until the entire 3D part is formed .That’s why the method is called (GMP) generation manufacturing process.
Historical development of Rapid prototyping :
Rapid prototyping developed in major three phases :
First phase: Manual Prototyping (Ancient – 1970s)
Earlier, prototypes were made manually by highly skilled craftsmen. In the 1970s all depended on wood, clay, wax, form plastics, metal & men’s skills. Although this method was slow, expensive at that time.
Second phase: Virtual Prototyping (1970s onwards)
After 1970s CAD and design software were developed and in this era design was started where CAD is used as creating 3D models using computer software. These soft models can Analyze stresses developed, model can be simulated & testing are virtually done. At this era only virtual testing & simulation was possible.
Third phase: Rapid Prototyping (1980s onwards)
Early 1980s Rapid Prototype introduced. All designing processes like CAD ( computer added design) matured, CAM ( Computer added manufacturing ) & CNC ( computer numerical control) etc became common for industries. Lasers, computers, and automation were improved. In this era Rapid prototyping developed and layer–by–layer manufacturing started.
Advantages of Rapid Prototyping:
Fast Production:- RP builds parts very quietly compared to traditional methods like machining or casting.
No need for tool or Moulds:- RP creates parts directly from CAD data, so no jigs, fixtures or moulds are required.
Complex shapes are easy:- Very complicated geometries, internal features & organic shapes can be made easily.
Reduces development time:- Designers can test, modify and reprint quickly, speeding up the product cycle.
Early error detention:- RP helps identify design flaws early before full-scale production.
Customization is easy:- Each prototype can be different without extra cost, making customization simple.
Cost effective for prototypes:- For low volume or one time prototype, RP is cheaper then casting or machining.
Supports iterative design:- Many design variations can be produced and compared rapidly.
Improves communication:- A physical prototype helps designs, engineers, management and clients understand the product better.
Suitable for small batch production:- RP can produce small numbers of function components economically.
Disadvantages of Rapid Prototyping:
Limited material strength:- Most RP materials are weaker than conventional materials like metals.
High cost for large parts:- Large objects are expensive and slow to produce.
Surface finish may need post processing:- RP surface may be rough and require sanding, painting, or finishing.
Limited material choices:- Only certain plastics, resigns and metal are compatible with RP.
Accuracy depends on layers thickness:- Thicker layers reduce accuracy & thin layers increase time and cost.
Machines are expensive:- Industrial TP machines cost a lot to buy and maintain.
Not suitable for Mass production:- TP is slow and uneconomical for high volume.
Design dependency on CAD skills:- RP fully depends on the quality of the CAD models therefore poor design means poor outputs.
Material properties can differ from real parts:- Prototypes produced may not match the final material properties(strength, durability).
Environment concerns:- some RP materials are not eco-friendly and have disposal issues.
Traditional Prototyping Vs Rapid Prototyping (RP)
Difference between Rapid Prototyping and CNC:
Applications of Rapid Prototyping parts:
Rapid prototyping parts are widely used in product development due to their fast fabrication and accuracy. The major usages of RP parts are -
Concept of visualization: RP parts are used to visualize the design concept of a product.
Design Verification: RP parts verify the correctness of design like from fit, assembly, ergonomics before final production.
Function Testing: RP parts are used to test the functional behaviour of components or assembly. Tests like Motion testing, Mechanism checking, assembly trails.
Manufacturing and Assembly analysis: RP parts are used to analyze, Easy of assembly, Interference between parts, Manufacturing feasibility. This helps in identifying manufacturing and assembly problems before mass productions.
Tooling and Mold making: RP parts are used to make, Patterns for casting, Molds and dies, tools inserts.
Customer Evaluation and Marketing: RP parts are used for Customer feedback, Market testing, Product demonstrations. Customers can handle and evaluate the product physically, which improves communications and decision making.
Medical & Engineering Applications: In medical it is used for making models of surgical planning, Prosthetics and implants, aerospace and automotive component development.