Week 3:- BiW Fixture Design Methodologies Challenges

DESIGN METHODOLOGY

Design methodologies contains some steps or concepts, with the help of that steps or concept we can design fixture. The steps cans be given as:

Purchase order

Input from the customer

Percentage Completion criteria

Design Output

1.Purchase Order (PO):

Purchase order is the official document which is received from the customer end.

The customer undertakes to pay the seller the sales price of a specific product to be delivered in the future.

Not only will this help you get off to a good start, but both parties can use it as a signature in case the order is not delivered as expected.

After getting the official PO, the project can be start.

2. Inputs From the customer: To start designing the fixture, we need inputs from customers which can be:

Functional Requirement: For what purpose the design needed.

Preferred Standards: While designing which kind of standard, we have to keep in mind.

Layout: Layout information data for flow of product, sequencing of assemble process, position of robots.

Ergo Data: Ergonomic data(data which study the human behavior and movements) are presented by the customer as an idea and the design of the fixtures should be made according to this information.

GD&T and Weld Study: Data related GD&T and Weld gun to be used.

Be Sure that the input data form customer end will be in official format(mail based). So in future any problem occur, this information will help a lot.

3. Percentage Completion Criteria: It's just like tracking sheet of Project status which used at design and Dispatch stages of welding Fixture.

Its includes different stages of project actives(%) follow as:

Input and concept design : 0-25%

Concept approval and Simulation check : 25-40%

Design Freezing and detailing : 40-80%

Check and Final Dispatch : 80-100%

4. Design Output: After completing with design shared the all cads files, layout files , 2D drawings of project should be share to the customer through official format(mail).

Input required to start designing Fixture

• The inputs that we get from the client to start the designing of the institution are as follows:

1. Functional demand : The inputs regarding the functional demand of the institution are entered from the client like for which process the institution needs to be designed. For illustration, welding institution, clinging institution, Checking institution Etc.
2. Standard Preferred norms : The client wants to follow some norms. These standard parts should be implement or used in our design which saves time and cost saving on the project. ABB, NAAMS, Tunkers are some norms. Some Parts like Clamps, Cylinders, switches, etc. are used on the basis of preferred norms of the company.
3. Car Products : Car Products :The inputs regarding GD&T, part lists, , pin Locating Points, Clamp plan ,Product assembly Process distance are received by a car product.
4. GD & T : It gives information about the position of pins, Rest, clamps, and slide unit information of each station.
5. Parts list : It gives information of part like part name, the part number of the part which is to be assembled in the institution of fixture.
6. Clamp Plan : Clamp plans give the position of pins, rests, clamp, dumps, etc. we need to consult with the client if we need to make changes in the clamp plan.
7. Product Assembly process sheet : It gives details about the sequence of the assembly including station details.
8. CAD files : The 3D model of the car part is needed for designing the institution of fixture for that particular part.
9. Layout : The layout provides information about the flow of the product, assembly sequence, the position of robots, sub-assembly links, accessories like tool changer and tip dresser, platform height.
10. Ergo data : Ergonomics defines as the study of human behavior and movements. The ergo data like the height, distance from the institution is given as an input by the client and the design of the institution must cleave to these data. This design will affect in ease of operation for the operator of the fixture.
11. Weld Study : Weld study gives information about the type of weld gun to be used for the process. Also, it gives information about the number of geo weld spots as well as the number of Re-spot welds. These spots will be indicated using red and green spheres independently.

Input from Car products

• After the Study of Car products, we will get following input which can be given as:

1. GD&T
2. Part lists
3. Cad Files
4. Clamp Plan
5. Product Assembly Process Sheet

1. GD&T : Provide the data on the geometric dimensions and tolerances of the part for which the fixture is designed. GD&T provides information for the location of pins and clamps, the main fastening components that hold the part to be machined.

2. Parts List : It contains a list of parts to be assembled into the fixture. A parts list includes information about part number, part name, part thickness, etc.

3. 3D CAD files : 3D CAD files are provided by customers for parts for which fasteners need to be designed.

4. Clamping Plan : Clamp plans indicate the location of pins, stops, clamps, dumps, etc. If the clamp plan needs to be changed, the customer must be consulted.

5.Product assembly Process sheet : It shows how the product moves from one assembly station to another and also provides information about which parts need to be assembled and at what stage. The assembly process cannot be changed without agreement with the customer.

Clamp Plan

• A clamp is a device used to securely hold parts in an assembly.
• Clamps prevent movement of the assembly in the fixture and ensure that the parts function properly without distortion.
• Clamps must be installed in a way that does not interfere with operation.
• Clamping plans are data provided by the customer.
• The clamping plan provides information on the location of pins, support assemblies, clamping assemblies, moldboard, etc.
• Provides detailed information about the exact location of the clamping points in coordinate format.
• In some cases, the clamp location may damage the tool or may be very close to the pin location.
• In such cases, you should not decide to change your execution method without discussing the matter with your customer.

Purpose of a layout

• The main purpose of the layout is to Show the overall area of ​​the workshop according to the work performed there.
• The layout provides information about product flow, assembly sequence, robot positions, sub-assembly links, accessories such as tool changers and tip dressers, and platform height.
• Part flow provides information about how parts move from one station to another. Station pitch provides information about the space constraints between two robots.
• A robot station is the location of a robot.
• The position of the tip dresser and tool changer is important for the robot to lower one tool into position and pick up another.
• The image above shows the layout of the assembly plan. The layout clearly shows the location of the robot and accessories.
• A circle drawn around a robot indicates the area that a particular robot is responsible for.
• The area being cleaned is within the reach of the specific robot and the attachment placement must be within the area being cleaned.
• Details of fixtures such as geographic fixtures are provided in the layout.
• Any changes to the layout should be discussed with the client.

Ergo Data

• Ergonomics is the science of improving product design to optimize products for human use.
• Human characteristics such as height, weight, and proportions are taken into account, as well as information about the human's hearing, vision, temperature preferences, etc.
• Ergonomics is sometimes also called ergonomics.
• Ergonomic data such as height and distance from the fixture are entered by the customer and the design of the fixture must comply with these data.
• This design makes the device operator's job easier.
• For example, assume that in the automotive industry, workers load and unload fixtures and perform the same process for eight hours a day.
• Therefore, the fixture must be designed based on ergonomic data provided by the customer.
• If these devices are poorly designed or improperly adjusted for human use, the person operating them may experience unnecessary fatigue, stress, and even injury.

Weld Study

• Weld inspection is important information obtained from customers.
• Welding surveys provide information about the welding torch, welding matrix, and welding points.
• The weld point is the point where the welding takes place.
• Weld points are very important data and changing these points may result in the part not being assembled correctly into the fixture.
• It also provides information on the number of geo weld spots and the number of repeated spot welds.
• These points are indicated by red and green spheres respectively.
• A Geo Weld point is a point that is welded to a Geo Fixture.
• This is important because it ensures that the assembly is not deformed when transported for reattachment.
• After geo welding, repeated spot welding is performed.
• These welds increase the strength of the assembly before joining it to another panel.
• Weld inspection is important in the automotive industry because every vehicle's BIW must have at least 5000 weld points.

Criteria For Percentage Completion in the Designing Stage

• It is used during the design and delivery stages of welding equipment.
• It displays the number of completed tasks in the project and helps you determine whether the work is being completed according to the planned schedule.
• Each stage of the project has different percentages as follows:

1. Input and Conceptual Design 0-25% : This is the initial phase of the project, where all initial data is received from the customer and a project design concept is created based on this data.

2. Concept approval and simulation validation 25-40% : Once the concept is developed, it is sent to the customer for approval and simulation testing is performed on the design to determine feasibility.

3. Design freeze and detailing 40-80% : Design changes are made based on simulation check results or if changes are suggested by the customer. Once all of these changes have been made, the design is finalized and detailed work on the design begins.

4. Verification and final shipment 80~100% : After detailed explanation, the product is shipped for quality control and finally shipped to the customer.

Output in Design

• The output is a 3D model and 2D drawing of the tool.
• There are two types of output tools: a. Unitized tools b. Non-Unitized tools

1.Unitized tools : Tools mounted on a common base, such as pin blocks, clamp blocks, and support blocks, are called integrated tools. These tools require two types of drawing sheets: key sheets and layout sheets.

a. Key Sheets : Provides information about unit indexing and placement in the tool base.

b. Layout sheet : This is a detailed drawing of the individual device, including all components.

2. Non-Unitized tools: Non-unitized tools are stand-alone tools, such as adhesive stands. I only need the layout and I can elaborate on that alone. Design deliverables should include the following items: Where possible, approved standard parts should be used. The design should be simple and economical. The design must meet all safety and ergonomic standards. Motion control must be considered for moving components. The weight of moving parts should be kept to a minimum without compromising strength. Controlled processing of parts without damage. The designer is responsible for checking all clamps and weld guns. The frame and structure must be simple and durable.

Structuring the design tree and error Reducing

• Constructing a design tree involves the process of giving all nodes and parts names according to certain standards.
• Each customer has their own set of standards for constructing their design tree.
• This is an important process that helps identify a specific part or assembly and determine which project and tool/block it belongs to.
• This helps prevent errors during design, manufacturing, assembly and testing.
• If parts and assemblies are not named correctly or if the design tree is not well organized, it can create confusion in understanding the design and create serious opportunities for mistakes to be made.
• The name of a fixture, subassembly, or part provides information about the project, tool, or subassembly to which it belongs.
• This can help you determine how many elements of the same type or different types are used in an assembly.
• Two or more parts with a similar design are given the same name so that one of them is used as a reference in production.
• In the design tree, the part we are designing should be at the top. Standard parts used by customers should be placed below the design parts list.
• Failure to place standard parts in the design tree will result in them being remanufactured, costing you both money and time on your project.
• Other standard or outsourced parts, such as fasteners, cylinders, etc., should be placed lower in the design tree.

Units and its Type

• Units are part of an integrated tool. There are two types of units: a. simple Unit b. composite Unit

1. Simple Unit: As the name suggests, simple devices have a simple structure and simple design and manufacturing processes.

Simple units are further classified as: Rest Unit, Fixed Pin Unit, Retract Pin Unit, Rough Locator Unit, Sensor Unit and Base Unit.

a. Rest Unit : The Rest unit are the units in which the components are placed. There is no top clamp and no force is applied. These type of unit typically have Rested mylar, risers, blades, etc. rain.

b. Base Unit : The base block is the block used to mount all other blocks, including clamp blocks, support blocks, and pin blocks. Other parts, such as automation blocks, are also mounted on the base Unit.

c. Fixed Pin Unit : A retaining pin is a retaining pin used to secure a part to a fixture.

d. Retractable pin Unit : The retractable pin block is located opposite the stationary block and can be moved up or down a certain distance. Used to lower complex panels after welding.

e. Slide Unit : Sliding Units are used in luminaires when space constraints are high, and using other elements to design the assembly is very difficult.

Fixed Pin Units

• Fixed pin Unit is used in fixing device to find the position of vehicle panel during operation.
• Pin, pin retainer, spacer, blade, lifting part are part of fixed pin block. Pin retainer is used to install pin.
• Pin retainer block has double sided spacer. It is very important when designing pin block because it helps to avoid overlap tolerance during assembly process.
• Purpose of the fixed pin assembly. The fixed pin assembly is used to fix the 6 DOF fixture assembly.
• The remaining 6 degrees of freedom are fixed by 3 support nodes. The pin helps to locate the assembly parts very accurately for welding operations.

Different parts of a fixed assembly

• The different parts of a fixed pin assembly are:

a. Pin : Pin is used to accurately position the parts to be welded in the assembly. The hole in the assembly part is inserted into this pin. The pin limits the freedom of the fixed part. The diameter of the pin has a tighter tolerance than the diameter of the hole in the part.

b. Pin retainer : Pin Retainer Pin retainer is used to hold the positioning pin. The pin retainer block has a double-sided spacer.

c. Shims : Shims is a small part with a thickness of 0.1, 0.2, 0.3mm. The spacer is used to compensate for the difference due to the assembly overlap tolerance, which will cause the panel to not be properly held if the mylar is not firmly held. On the other hand, if the mylar is very tightly held to the panel, a dent may be created in the panel. Spacers play an important role in adjusting the mylar to a specific position.

d. Blade : A blade is a plate that is attached to a lifter. A cylinder and other additional levers are mounted on the blade.

e. Riser : A riser is a component used to increase the height of a fixture. The riser is attached to the fixture base and the blade is mounted on the lifter. There are two types of lifts. 1. L-type risers 2. Square tube Raisers.

Purpose of creating a Rest Unit and its parts

• The Rest Unit is designed to support the car panel using Mylar. The main purpose of the Rest Unit is to support the car panel.
• The Rest Unit consists of: Mylar, Blade, Riser.

1. Mylar : Mylar is the part that holds the top and bottom of the panel in place when in operation. The top of the mylar is called the clamp mylar. The bottom of the mylar is known as the backup mylar. Each clamp mylar has a support mylar. It holds the panel in place during the welding process to prevent it from deforming. The image below shows the base clamp and the support mylar.

2. Riser : A Riser is a component used to increase the height of a fixture. The lifter is attached to the fixture base and the blade is mounted on the lifter. There are two types of lifts: 1. L-type Riser 2. Square tube Riser.

3. Blade : A blade is a plate that is attached to the lifter. Cylinders and other additional levers are mounted on the blade.

Basic principles of designing a Sensor unit

• The sensor unit is used to detect whether the car panel is installed in the fixture. The sensor sends a signal to the PLC system, and the following process is executed based on the signal.
• The number of sensors used in the fixture depends on the number of parts used in the assembly.
• Each panel should consist of one or two panels, depending on the size of the parts, in which case they are placed in opposite directions.
• The sensor should be installed so that it can be adjusted in three directions. Major sensor manufacturers include IFM, SICK, OMRON, etc.
• The types of sensors used are as follows:

1. Proximity sensor: A proximity sensor is a sensor that can detect the presence of an object nearby without physical contact. Proximity sensors often emit an electromagnetic field or a beam of electromagnetic radiation (e.g. infrared) and monitor changes in the field or response signal.

2. Laser Sensors : A laser sensor is a type of sensor that uses laser technology to measure. It usually consists of a laser, optical components, and a photovoltaic device. It can convert the measured physical parameters (e.g. length, flux, speed, etc.) into an optical signal, and then use a photoelectric converter to convert the optical signal into an electrical signal.

3. Photoelectric Sensor : A photoelectric sensor consists of a light source (LED), a receiver (phototransistor), a signal converter, and an amplifier. The phototransistor analyzes the incoming light, determines whether the light comes from the LED, and triggers an output signal accordingly.

Rough locator Unit and the basic principles to consider when designing one

• A rough locator helps the operator place the part in the correct location and orientation. A rough locator can be a standard part or a manufactured part.
• The basic principle of operation of the rough locator is as follows: The rough locator should be positioned and guided along the edge of the cockpit panel.
• There should be a gap of 2-5 mm between the rough locator and the cabin panel to avoid damage during loading and unloading.
• The rough locator should be positioned at the same angle as the cockpit panel. The rough locator should guide the panel in the direction of the pin fixation.
• The rough locator should start guiding the panel 10-15 mm before the pin engages. The rough locator should be designed for an entry angle of approximately 35-40 degrees into the cabin panel.
• The rough locator should be designed with two mounting slots for easy adjustment. The slots should be oriented toward the guide section of the vehicle.

Base unit and its parts

• The Base Unit is designed to mount all other unit of the tool, such as the clamp unit, pin unit, support unit, etc., and other parts, such as the pneumatic valve box, cable duct, etc., are also installed on the base unit.
• The basic unit consists of the following parts: Valve box, Truncking channel, Measuring hole cover, Eyebolt, Pedestal, Floorplates.

1. Valve box: The valve box is used to supply power to the pneumatic cylinders assembled on the fixture. The valve box consists of inlet and outlet solenoid valves that control the air supply to the cylinders.

2.Truncking Channel: The Truncking Channel is an empty passage that guides and closes the pneumatic and electric pads.

3.Measuring hole cover: The measuring hole cover shows the coordinates of the measuring hole. These coordinates are used as reference coordinates for positioning other blocks and for CMM inspection purposes.

4.Eye Bolt: An eye bolt is installed on the base unit to lift the base unit and move it from one location to another.

5.Pedestal: The pedestal is a stand-type structure on which the entire base unit rests.

6.Floorplates: The Floorplates is used to mount the entire base unit to the floor.

Dump Unit and its function

• Dump Unit are used in complex installations. Dump Unit are used when there are geometric restrictions on the panel layout.
• They consist of a release cylinder that performs the clamping and releasing operations.

Sliding Unit and its uses

• Sliding blocks are used in fixtures with space constraints where it is difficult to design an assembly using multiple blocks.
• The sliding block consists of a sliding cylinder to which a panel is attached.
• The panel moves along the guide, and this movement is caused by the reciprocating motion of the cylinder.
• The position fixing block is used to fix the position of the panel on the guide.
• The sensor is used to detect whether the sliding plate has reached the desired position.
• The stop block is used to control the movement of the sliding plate.

References:

1. Google

2. Skill-lync