Process of building an engine

The building of an engine includes 3 processes: machining, assembly, test.

In machining shop, there’re operations of cylinder body, cylinder head, crankshaft. Numerical controlled work centers are used to cut metal pieces into target components.

The key functions of MES in machining shop:

1)       Traceability of raw parts serial number and lot number.

2)       Monitoring of machine status.

3)       Monitoring of key process parameters.

4)       Data collection of key test result such as of leak test.

5)       Scrap management.

System is not required to manage orders.

Monitoring device status can act quickly to abnormal situations.

The traceability of raw parts and key process parameters, is very helpful while it’s required to call back products by batch.

 

Key processes of assembly shop:

1)       Cylinder head sub-assembly.

2)       Piston sub-assembly.

3)       Interior assembly.

4)       Exterior assembly.

5)       Cold test – test without starting up engine.

 

Assembly shop is managed by scheduled orders. If production line supports multiple models, then it also requires just-in-time material handling. And the most important stations are assembly stations and torque stations.

The key functions of MES:

1)       Release orders to lift-on stations.

2)       Material error proofing.

3)       Key parts traceability.

4)       Torque error proofing.

5)       Travel record and broadcast, and interface for material handling.

6)       Device monitoring.

7)       Quality call.

8)       Quality defect management.

9)       Data collection of gap detection and cold test.

 

Hot test means to start up engine, and simulate real working situation and worst conditions, and record the running data.

Hot test usually uses custom test stations and software, and MES collects test data via interface.

 

Diagram 1.3-1 shows key process of engine plant:

Diagram 1.3-1: key process of engine plant

 

 

Building Commercial Vehicle - MES in Vehicle Manufacturing

Commercial vehicle include truck and bus.

Commercial vehicle uses chassis to support its weight, while it’s body in case of passenger car.

The high level building process of a commercial vehicle includes: punching & welding & painting of body, punching & riveting & painting of chassis, and final assembly.

The features of commercial vehicle plant are: less annual production output, longer cycle time of each station, larger station distance, and lower requirement of automation and just-in-time.

Commercial vehicles especially trucks have very long service time and very big driving distance, so they have very high requirement of durability for key parts. So riveting is used for assembly of chassis, and it’s highly controlled for tighten parts.

Key functions of final assembly shop:

1)       PBS – Painted body store;

2)       Vehicle location monitoring and broadcasting;

3)       Assembly sheet printing;

4)       Work instruction;

5)       Traceability of key parts;

6)       Error proofing of key parts;

7)       Quality and defect management.

 

Diagram 1.2-1 shows main process of final assembly:

Diagram 1.2-1: main process of final assembly

 

Diagram 1.2-2 shows overall process of building a commercial vehicle:

Diagram 1.2-2: overall process of building a commercial vehicle

 

Process of building a passenger car (MES in vehilce manufacturing)

Normally passenger cars include family car, SUV and MPV.

Car body is the main frame of a car, is welded by steel plates, and then chassis, engine, transmission, interior are assembled into car body. The car body is welded into a cage form, to expand car space and reduce impact from outside damage.

The building process of a passenger car has 4 parts: punching, welding, painting, and assembly.

3D CAD software is used to design car body, and the 3D model is also used to design metal sheet and fixtures.

In welding process, process engineer will use 3D CAD model to design punching fixtures. The punch machine will setup fixtures and load rolls of metal sheet, and output component sheet according to the fixture. In punch shop, MES key function is to monitor real time status of devices, because its availability decides whole operation efficiency.

In welding process, robots will weld component sheet into car body. The welding quality has big impact to vehicle safety. The professional software is used to measure the gap between designed welding points and actual welding points. The welded car body will be transferred to WBS(Welded Body Store).

The key operations of welding:

1)       Welding engine cabinet, front floor, back floor.

2)       Weld these 3 parts into car frame.

3)       Weld left side and right side.

4)       Weld left/right sides into car frame.

5)       Weld doors.

Below diagram shows key components of car body:

Diagram 1.1-1: key components of car body

 

Below diagram shows key welding process:

Diagram 1.1-2: key welding process

 

In Weld shop, MES key functions is to download Orders to Lift-on stations, such as Engine cabinet, front floor, back floor, left side, right side. MES downloads Sales Orders from ERP, then generate Work Orders, and then sequence Work Orders, then downloads to machine PLCs. Machines/robots will build car components based on model type and Order attributes stored in PLC.

In painting process, a car body will take bottom painting, middle painting, top painting, and heating operations. Most operations will be operated by machines. The painted bodies will be transferred to PBS(Painted Body Store).

Painting shop has lots of process segments, most of them will be done by machines automatically, and can also be repaired by manually. MES together with PLC can deliver cars to repair areas automatically.

Below diagram shows key painting process:

Diagram 1.1-3: key painting process

 

In final assembly, car needs to install Trim, Chassis and all other components, and will run test.

Key process includes:

1)       Transfer vehicle from PBS based on route rules.

2)       In front trim line, install passenger cabinet parts, dashboard, sunroof.

3)       In chassis line, install chassis, engine, transmission.

4)       In back trim line, install tires, chairs, doors.

5)       In final line, install accessories, fill liquids, take visual inspection.

6)       In test line, write software, and test wheel positioning, lamps, gas.

7)       Building in sub-assembly lines such as doors, dashboard, engine.

In final assembly shop, most parts are assembled by manually, it relates delivery of lots of materials. MES key functions include: assembly instruction, error proofing, material pull, equipment integration.

Below diagram shows key process of final assembly:

Diagram 1.1-4: key process of final assembly

 

                Below diagram shows over all process of a car plant:

Diagram 1.1-5: over all process of a car plant

Planning - MES in Vehicle Manufacturing

Due to unique process of vehicle building, the planning of MES implementation is very different than general software system.

 

1.    Milestones

Building a vehicle plant has these milestones:

-          TT, short of Tool Tryout, or Tooling Trial, is referring phase of equipment setup and configuration, MES is cut-over during this phase.

-          PP, short of Pilot Production, the Logistics Execution System is cut-over during this phase.

-          SOP, Start of Production, ERP system is cut-over during this phase.

For ERP system, normally we’ll setup test system at first, then prepare master data, then configure and test, finally load data to production system, and cut-over during SOP.

But for MES, it needs to integrate with lots of equipment, and we must use time window of TT to test.

Normally on TT phase, there’re few vehicles available for test, only a couple of vehicles for each shop, and will stop in case of any issue. But since PP, the daily planning quantity will increase, so it’s not suitable for handling any test related to interface with equipment.

There’ll be a couple of months between TT and SOP, which brings a challenge of project management: MES and ERP are normally managed by same IT program, but since they have different cut-over time, so it will be quite difficult to align planning and resource.

 

2.    Develop pattern

MES is cut-over at TT, which brings concern of develop pattern.

In recent years, affected by internet development, agile develop pattern is quite popular, but in vehicle building MES area, traditional waterfall + modular pattern is more suitable.

Consider that equipment integration should be ready and tested in TT phase, and ERP interface should be tested in SOP phase, so we need to develop and test equipment integration module in advance.

Another feature of MES is: Normally we setup production system, then develop and test in that system directly. There’re 2 reasons: firstly, the test of OPC&PLC must be referred to physical servers, the successful test on test system doesn’t mean success on production system. Secondly, in production system, there’re availability mechanism such as data guard of Database, load balance of Web Server, and cluster of Application Server, and such features cannot be tested in test system.

 

3.     Equipment Debugging

For MES, the debugging/test of equipment integration are planned at TT phase, when the plant is still under construction, for some area the power and network might not be available yet, which requires temporary power and network, so lots of stations might need a couple of turns of debugging.

Each function module should go through these debugging process:

-          Power and network test, to check infrastructure such as O/S, client, network.

-          Communication test, also known as heart beat test. Equipment PLC sends out a heart beat signal, then MES receives it and responses back. This step is to check the basic handshaking between equipment and MES, it could also check communication parts such as Couplers.

-          Virtual business test. Before physical vehicle is available, PLC/HMI sends out virtual business data, then MES responses according to business logic and handshaking protocol accordingly. The reason is that there’re only few vehicles available at TT phase, and there’re lots of stations require debugging, so we need to do as many tests as possible while IE engineers are available.

-          Physical vehicle test. It happens after virtual business test, to check the physical devices such as sensors, encoders, and also do final test of whole process.

In debugging phase, different debugging process might happen in same time. For example in Welding Shop, there’re 10+ IE engineers, but only 1 MES engineer, so the MES engineer might debug heart beat at one station in the morning, and test virtual business at another station in the afternoon.

As per detailed time planning, we should reserve 1 week for the 1^st station covering all test process, because the 1^st station covers lots of common issues such as setup of OPC and Gateway. Then for 2^nd and 3^rd stations 3 days should be reserved for each one. After that reserve 1 day for each later station. 2 weeks later reserve half day for each later station.

 

 

Communication management (MES in vehicle manufacturing)

In vehicle manufacturing, MES is a very complicated system, covering functions of planning/production/process/equipment/quality, relates to lots of process, and needs to cooperate with lots of departments.

Besides that, for a large vehicle company, it’s also required to handle the relationship between corporate departments and plant departments.

Below chart shows a typical MES organization architecture of a vehicle plant.

Diagram 4.1-1 MES organization architecture

 

We can see that, from MES point of view, as an execution system, MES’ direct customers are production executors(operators and machines), the other departments of plant should support production, and all departments of corporate should support local departments accordingly.

Besides that, while building a new plant, it’s designed by corporate departments on early stages, and then designed by plant departments later, and there will be gaps between corporate and plant regarding some process or requirement.

So during MES implementation, we will face these 2 challenges.

 

Challenge 1: how to understand business?

In recent years as concept of Industry 4.0 has been introduced to public, MES market is expanded, and more and more talents joined into MES area. But the fact is, there’re still not many people understand the process and requirement of vehicle manufacturing.

So it’s inevitable that lots of gaps between business and IT on requirements will happen.

To reach high understanding, we need to innovate in organization architecture.

Now let me introduce a best practice: Cummins MES.

Cummins MES is a corporate system, developed by one team globally, implemented by one team globally, operated by one team globally.

The develop team is based in headquarter, team members include IT talents(architect, technical experts, vendor experts) and business talents(business experts, control experts), running as a virtual team.

The business experts have 10+ years of experience in engine building, they’re very familiar with building process and quality standards. They will talk with process engineers and quality engineers to understand all details of any new requirement, and try to align between different plants. So the requirements submitted by business experts are really the thoughts of plants.

The control experts know how to control lineside devices and how they are interact with MES. They will talk with control engineers and vendor engineers, to define standard control protocols.

IT team members are working in same office with business experts and control experts, so IT can work closely with business and avoid misunderstanding during communication.

 

Challenge 2: how to align business?

Now lots of vehicle makers are large companies, with plants located worldwide. So even on implementing universal MES, there will be gaps for different plants.

From corporate’s perspective, MES should be designed to be standard solution, and to use one team to develop, deploy and support.

So how to balance corporate standards and plant customization?

Here I introduce a method for reference.

We can setup 2 expert committees, MES business experts committee, MES control experts committee. The team members should be experts from corporate and plants. Each expert has vote right, while corporate experts have more vote weight.

So while one requirement cannot reach alignment, we can arrange a vote inside experts committee, and get an agreement with highest vote score. The develop team should develop based on it as standard template. If a plant still need customization, then develop team can realize it during implementation with lower priority.

 

 

Journey of a bolt (MES in vehicle manufacturing)

In this article, I will take an example of a bolt, to explain how WMS(Warehouse Management System) and MES(Manufacturing Execution System) are used and integrated.

Bolt is a class of key components, has big impact to engine quality.

Below table lists out key process control points:

Area	Station/Position	Operation	System
Warehouse	WM100	Store components in box	WMS
Kitting	WM200	Pack bolt with spring and other materials	WMS
Assembly	OP10	On assembly completed, call for material pull delivery automatically	MES à WMS
	OP20	Manual assembly, manually call for material pull delivery if necessary	MES à WMS
	OP30	Pre-tighten bolt by manually	MES
	OP40	Final tighten bolt by robot	MES

 

Below chart shows high level process:

 

Now let’s analyze it from perspective of material delivery, assembly and material pull.

 

1.       Material delivery

Delivery of bolt has 3 big steps:

1)       Receives in bolt from vendor’s cargo, unpack and inspect, and then transfer to specific storage area in warehouse, with position WM100.

2)       Transfers bolt from warehouse to kitting station WM200, here operator packs bolt with spring and other components together.

3)       Uses AGV to transfer packed bolt to assembly station OP20.

To match with such requirement, we need to set below BOM info in WMS:

Material	Description	Stock No	Position
BT0010	Bolt xxx	10	WM100
BT0010	Bolt xxx	20	WM200
BT0010	Bolt xxx	30	OP20

 

2.       Assembly

Assembly of this bolt includes 3 stations:

1)       In OP20, operator put bolt into right position. In this example, we have quantity 4 of this bolt.

2)       In OP30, operator uses torque gun to pre-tight the bolts. If the station has been configured with 8 torque guns, and here we only need to user gun 1-4.

3)       In OP40, robot will final tight all bolt, with sequence of 1-4-3-2.

Then the assembly BOM should be:

Station	Material	Quantity
OP20	Bolt xxx	4
OP30	Bolt xxx	0
OP40	Bolt xxx	0

When engine arrives at station OP20, stack light of bolt will turn on, until operator picked 4 times, then stack light will turn off.

 

The torque gun error proofing is configured in MES:

Station	Gun#1 clicks	Gun#2 clicks	Gun#3 clicks	Gun#4 clicks	Gun#5 clicks	Gun#6 clicks	Gun#7 clicks	Gun#8 clicks	Sequence
OP30	1	1	1	1	0	0	0	0	00000000
OP40	1	1	1	1	0	0	0	0	14320000

In OP30, after gun 1/2/3/4 has completed tightening, error proofing of the gun is completed; when all 4 guns has completed tighten, then the error proofing of this station is completed, then PLC allows engine to leave.

In OP40, robot will tighten bolts with sequence of 1-4-3-2.

 

3.       Material Pull

In this example we have 2 layers of material pull: 1) assembly to pull from kitting; 2) kitting to pull from warehouse.

When assembly of OP10 is completed, MES will generate a travel record, and sync it to WMS, WMS will alert operator of WM200 to do kitting before engine comes to OP20.

When assembly of OP20 is completed, and if operator finds he doesn’t have enough material for next engine, then he can call for material with push button, the call message will be transferred to kitting area via WMS.

The logic of kitting area pull: each time AGV delivers material to assembly area, WMS will decrease material number of bolt in WM200, when the number is less than safe storage number, then WMS will send the pull message to mobile device of warehouse delivery operators, so they can deliver it from warehouse accordingly.