Week 3:- BiW Fixture Design Methodologies Challenges

1.What is design methodology in fixture design

Design methodology is nothing but the steps followed during the concept designing stages of fixture design.

2.What are the inputs required from the customer to start designing a Fixture?

The following are the inputs that are to be get from the customer to start designing a fixture

• Functional requirements.
• Preferred standard components.
• Car products.
• Ergo data.
• Weld study.
• Standard detailing templates.

3.What is the input we get from "Car Products"?

• GD&T.
• Part list.
• Cat files of car part.
• Clamp plan.
• Product assembly process sheet.

4.What is the purpose of a Layout?

Latout provides information of parts such as

• Flow of parts.
• Station pitch.
• Robot stations.
• Accessories like tool changer and tip dresser.
• Sub assembly links.
• Platform height.
• Loading unloading sequence heights.

6.what is ergo data?

Ergo data is nothing but the data or inputs which gives the human factors engineering data, between the operator & his working environment

7.What is weld study?

Stud Welding, more correctly termed drawn arc stud welding, is an electric arc process that rapidly joins a fastener to a base metal or substrate. The fastener can take many forms: threaded, un threaded, tapped etc. Both the fastener and the substrate can be of various materials including: steel, stainless steel, aluminum etc.

Weld studt includes the following

• Weld gun details.
• Weld matrix and weld points.

Geo weld points.

Re-spot weld points.

Equipment Needed For Stud Welding

Stud welding requires four essential pieces of equipment:

• power supply
• stud welding gun
• cabling
• weld studs

In addition to the welding equipment above, there are many stud welding accessories that help make the process easier such as grips,ferrule holders, and spark shields.

8.What are the criteria for percentage completion in the designing stage? Explain it in detail

The percentage completion criteria is followed in designing stages and dispatch stages of the welding fixtures

0-25% Input and concept design

25-40% concept approval and simulation

40-85% design freezing and detailing

85-100% Check and final dispatch

9.Brief about "Output" in design?

The design output is the 3D models and the 2D drawing of tools.Unitized tools(multiple units on a common base)require two types of drawing sheets

• Key sheet-an index of units and their placements on the tool base
• Layout sheet-A detailed drawing of individual units to include all of their components

Non Unitized tools-Tools that can stand alone and can be detailed completely on a layout sheet

The output should the following points

• Approved standard components are to be used wherever possible
• Design must be as simple and economical as possible
• Design must comply with all safety and ergonomic requirements
• The weight of moving parts must be kept to a minimum maintaining the maximum strength
• Frames and structures are to be simple and sturdy
• Motion control must be considered to any moving equipment’s
• Designer is responsible to validate clamps and weld guns

10.What do you understand by structuring a design tree? How does it reduce errors during the design process?

• Structuring a design tree implies a process where all the assemblies and parts are named in specific standards different customers have a set of standards to structure a design tree
• It is an important process that helps us to identify a specific part of the assembly as to which project tool or unit it belongs to
• This helps us to avoid errors during design study manufacturing assembly inspections etc
• If the parts are assembled ate not named properly on the design tree is not structured properly it will create confusion to understand the design may create major possibilities of making errors
• It can help us to identify the number of items the same type of different types that ate being used in an assembly.

11.What are Units? Mention 5 types of units.

• Fixed pin unit
• Retract pin unit
• Clamp unit
• Rest unit base unit
• Rough locator unit
• Dump uint
• slide unit
• Complex unit

12.Describe Fixed Pin units & their purpose?

Fixed pin is a unit designed to locate the car using pin. As the name suggest it uses a fixed pin which cannot be moved by any distance. The top most part is the fixed pin which will be used to locate the part. The part will have entry hole in which the pin will enter to arrest the motion of the part.

Their purpose is to constrain some degree of freedom by preventing from rotation of part.

13.what are the different parts of a fixed unit in fixture

• Pin
• Pin retainer
• Shims
• Blocks
• Blade and
• Riser

14.What is the purpose of making a Rest unit & describe its parts?

Rest unit is one of the simplest unit in fixture used with myler. As rest unit is simple to manufacture and require low cost, hence rest unit is combine with clamp unit and location unit. Rest unit consist of following parts:

Riser: These are used to increase height of unit and these are standard parts so need not detailed it or designed it.
Shims or Spacer: These are used to compensate tolerance stack up. In pin unit we need to control two direction that are X & Y using shims or space. Shims are generally thin sized plates used in group called shim pack and spacer are used as single plate and can be machined accordingly.
Blade: Blades are bolted on riser as shown
Mylars: These are the parts in the rest unit which are in contact with car panel or component used to give support or rest to the component.

15.What are the basic fundamentals to design a Sensor unit?

The sensor unit is designed to mount the sensors to inspect the weld on the part

The panel should be welded by the tool should be inspected by multiple sensor

The sensor should be mounted in such a way to all side of welding.It reduce the cost to manpower.It reduce error and keep the parts as dimension given in drawing.

Some of the example sensors are

• IR sensor
• Laser sensor
• Proximity sensor

16.What is a Rough locator unit & what are the basic fundamentals to consider while designing it?

Rough locators are used to help locate work pieces in the automation process. Locating refers to the desired location where you want the work piece to be when it is getting worked on either by a person, team, or robot.It is a device to establish and maintain position of a part in a jig or fixture.

The basic fundamentals to consider while designing it

Rough locators should be placed at the edges of the car panel, which has to guide.

Rough locators should be placed in the same angle of the car part edge with a minimum distance of 2 - 5 mm from the edge of the car part.

Rough locators should guide the panels in pin assembly direction in general.

Rough locators should start guiding the panel before 10 t0 15mm to the start of the pin engagement.

Rough locators should be designed with entry angle for car part entry as shown in the above figure 1.

Rough locators should be designed with two slots to mount for easy adjustments in general.

The slots should be in the direction of car part guiding.

17. What is a Base unit and describe it's parts?

Base Unit is the unit designed to mount all the other units of the tool also other parts necessary for a tool like parametric valve box, trucking cable path will also be mounted on to a base unit
Parts in Base unit:-
- Trunking channel
- Base plate
- Valve Box
- Measuring hole cover
- Eye bolt
- Pedestal
- Weld Bars
- Floor plate

18.What is a Dump Unit and what are its functions?

It is used to create an unit, at where the space is in sufficient for an unit. So this is a complex unit consist of dump cylinder used for clamping or un clamping of car panel or component.the cylinder consist of specific force and stroke for clamping and un clamping.

Function: Due to space constraints dump unit used in fixture,the cylinder is opened to clamp and closes to un clamp and this is vice versa for some other cases.

19.What is a Slide unit? Mention where Slide units are commonly used.

It is used to keep the fixture,weld gun,robots in or at a particular position.the entire unit is slide along the sliding rail consist by the unit for further operation.so slider units are most commonly used where there is the actuation in the specific direction is not possible.These sliding unit is commonly used in automotive industry for different similar components.