knowledge and planning system for distortion engineering

Preprint (as submitted): To be cited as follows: Thoben, K. D., Klein, D., Wuest, T., & Zoch, H. W. (2012). Knowledge and planning system for distortion engineering. Materialwissenschaft und Werkstofftechnik, 43(1‐2), 192-198.

Knowledge and Planning System for Distortion

Engineering

Klaus-Dieter Thoben1, Dieter Klein

1, Thorsten Wuest

1, Hans-Werner Zoch

2

1 BIBA – Bremer Institut für Produktion und Logistik GmbH, Hochschulring 20, 28359 Bremen,

Germany, {tho, kln, wue}@biba.uni-bremen.de 2IWT – Stiftung Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen, Germany, zoch@iwt-

bremen.de

Abstract

Presented will be a process-oriented knowledge and planning system for a structured depositing and locating of

findings along manufacturing processes for component distortion. In the focus of this article are the reasons for the

chosen structure and the presentation of the model for implementation of this system. It is shown that the findings

must be seen first in connection with a process chain. A further evaluation of the findings will show that information

can then be generalized to sub-process chains. The findings can be accessed from a knowledge perspective to be a

basis of new experiments, but also be used for archiving of knowledge. The planning view for example is suitable to

help a planner to set up a process plan. The system is designed in a way that it can be easily extended by new

findings. Concluding, the functioning of the system will be illustrated by two practical examples.

Keywords

Finding, knowledge system, planning system, distortion, recommendation

1 Introduction

After ten years running many findings in the Collaborative Research Center CRC 570

“Distortion Engineering” were generated in form of knowledge about influencing factors,

mechanisms and compensation strategies for distortion. This knowledge came up mainly from

experiments, simulations and material investigations as well as from the exchange between

experts. These findings should be used to implement a knowledge and planning system. With the

help of the knowledge system the findings should be prepared to support further experiments. By

the planning system on the other hand the findings should be selected to support planning of

manufacturing processes. To implement the system the procedure was as follows. At first the

findings should be deposited in a structured way. Then, in the next step the knowledge and

planning system has access to these findings. The findings have to be always interpreted and

evaluated from a perspective including the entire manufacturing process first. Furthermore, the

findings depend on the individual material and the geometry.

……

•Processchain 1

•Material

•Geometry

•Processchain 2

•Material

•Geometry

Finding1 Finding 2 Finding n

Figure 1: Structuring findings


The findings should be ordered in three categories that they always belong to a process chain, a

material and a geometry (see Figure 1).

Because the findings are only valid and can only be interpreted within the framework of the three

categories, data about the manufacturing process (like temperature) as well as the chemical

composition and the geometry have to be considered together with the findings. While the focus

of this article is based on the structure of the system and not on the interpretation of findings it

will be refered to literature where the data are already mentioned [Kusmierz et al. 2003], [Kessler

et al. 2003], [Clausen et al. 2004], [Clausen et al. 2006], [Kessler et al. 2006], [Acht et al. 2008a],

[Acht et al. 2008b], [Sölter 2009]. To structure the findings of the knowledge system, the method

“Distortion Engineering”, introduced by the CRC 570 was applied [Zoch 2009]. To structure the

planning system the general procedure after [Eversheim 2002] will be used, with focuses on the

planning perspective of cutting.

Following this explanations the knowledge and planning system of the CRC 570 was developed.

This article describes first the structure of the knowledge system. Secondly, the structure of the

planning system is introduced. On the basis of two exclusive findings of the CRC 570 the

functionality of the system is finally pointed out. For a better understanding it should be

mentioned here that the presented Figures 3 and 4 describe the respective structure of the view

and were finally added together in Figure 5 to show the entire knowledge and planning system.

2 Knowledge System

Distortion has to be considered as a system attribute [Hoffmann et al. 2002]. To make such a

system accessible, a suitable method is needed. One possibility to research and understand the

causes in a structured way and further to use the knowledge for compensation is demonstrated by

the “Distortion Engineering” methodology. The method is described in detail in [Lübben and

Zoch 2008], [Zoch 2009]. The method is divided into three stages (see Figure 2).

Stage 1

Stage 2

Stage 3

Stage 4Transferability on other geometry,

materials and process chainsGeneralization

Me

tho

do

log

y„D

isto

rtio

nEngineering“

Su

pp

lem

en

t

System, Actuating + Process Variables

Design of Experiments (DoE)

Process Chain

Carriers of Distortion Potential

Distortion Mechanism

Actions for

Compensation of Distortion

Simulation / Modeling

In-Process-Measurement + Control

Compensation

Mechanisms

Influencing Variables

Distortion

Figure 2: Relationship between the extended methodology and the levels of findings modified after

[Luebben 2008], Zoch [2009]

In the first stage the determination of influencing factors takes place whereas the method

“design of experiments” is often used. In the second stage the description of the distortion

mechanisms is in the focus, based on carriers of the distortion potential. For the quantitative

https://www.researchgate.net/publication/37932813_Verzugsverhalten_von_geschmiedeten_Lagerringen_aus_100Cr6?el=1_x_8&enrichId=rgreq-1b7dcb27-f09d-418e-ac80-36963ea3d2ac&enrichSource=Y292ZXJQYWdlOzIyMjczNzcyOTtBUzoxNjc2OTU1Njc4MjY5NDVAMTQxNjk5MzE0NzQ4Mw==

https://www.researchgate.net/publication/230366327_Experimental_Study_of_Distortion_Phenomena_in_Manufacturing_Lines?el=1_x_8&enrichId=rgreq-1b7dcb27-f09d-418e-ac80-36963ea3d2ac&enrichSource=Y292ZXJQYWdlOzIyMjczNzcyOTtBUzoxNjc2OTU1Njc4MjY5NDVAMTQxNjk5MzE0NzQ4Mw==

https://www.researchgate.net/publication/229904599_Distortion_engineering_Vision_or_ready_to_application_distortion_engineering_Vision_oder_schon_praxistauglich?el=1_x_8&enrichId=rgreq-1b7dcb27-f09d-418e-ac80-36963ea3d2ac&enrichSource=Y292ZXJQYWdlOzIyMjczNzcyOTtBUzoxNjc2OTU1Njc4MjY5NDVAMTQxNjk5MzE0NzQ4Mw==

https://www.researchgate.net/publication/229904599_Distortion_engineering_Vision_or_ready_to_application_distortion_engineering_Vision_oder_schon_praxistauglich?el=1_x_8&enrichId=rgreq-1b7dcb27-f09d-418e-ac80-36963ea3d2ac&enrichSource=Y292ZXJQYWdlOzIyMjczNzcyOTtBUzoxNjc2OTU1Njc4MjY5NDVAMTQxNjk5MzE0NzQ4Mw==


description of the mechanisms, modeling and simulation are used. In the last stage, these

mechanisms can be also used for distortion compensation by inverse approaches.

Following this method the knowledge system of the CRC 570 was developed. The findings were

categorized in such a way, that they are assigned to one of the three stages of this method. The

first category concerns findings of the first stage. They are usually very special, since they refer

to an individual geometry, an individual material and a special process chain. Findings about

mechanisms respectively derived tendencies belong to the second category. In the third category

findings regarding compensation approaches are mentioned. These approaches originate from

the understanding of mechanisms or from experiments. Additionally a fourth category

“generalization” was introduced which contains generalized findings in form of transferability

on other geometries, materials and process chains.

To build up a knowledge view to sort and locate the findings the system should consist of the

following categories which were highlighted bold in the text before (see also Figure 3):

Influencing factor (IF)

Mechanism (M)

Compensation (C)

Generalization (G)

……

User

Knowledge view

Main structure Categories of findings

Finding Process

chain

Material Geometry Influencing

factor (IF)

Mecha-

nismen (M)

Compen-

sation (C)

Generali-

zation (G)

Finding

1

1 100Cr6 Cylindrical

ring

IF1 - - G1

Finding

2

1 100Cr6 Cylindrical

ring

IF2 - - -

•Processchain 1

•Material

•Geometry

•Processchain 2

•Material

•Geometry

Finding1 Finding 2 Finding n

IF M C G

Figure 3: Correlation between knowledge view and findings

The aim of the user of the knowledge system is to look up findings sorted by the categories like

influencing factor to support him by further experiments. The table in Figure 2 shows that it is

not necessary that all categories have to be filled up with findings. Finding 2 only gives a

statement about influencing factors. At this point it has to be mentioned that findings of

influencing factors that show no influence on distortion should be integrated in the system. In

such a case the influencing factor should not be examined twice. Looking at the example of

Figure 3 it can be seen, that in the category of the influencing factors two findings are listed (IF1

and IF2). By the sum sign it should be denoted that in the category several findings exist

respectively can be located.


3 Planning System

These same findings (finding 1 and 2) can also be used for planning. Therefore the findings were

prepared in form of recommendations to support a distortion controlled process planning. While

the former view represents the knowledge in this view the planning system will be build up. The

goal of this view is to support a process planner to create a process plan for distortion control.

Taking the procedure of [Eversheim 2002] to plan a process in cutting five tasks have to be

worked out:

Determination of raw part

Determination of process sequence

Selection of manufacturing equipment

Determination of adjusting parameters

and determination of target time

By determining the raw part a suitable forging part should be selected while by determining the

process sequence the cutting sequences are planned. By selecting the manufacturing equipment

the cutting machine and the cutting tools are selected. In the case of determining the adjustment

parameters the cutting parameters are meant and by the determination of target time it is possible

to evaluate the process economically.

To work out these tasks the planner needs the following information which he will get from the

recommendations derived from the findings (see Table 1).

Task areas Categories of recommendation

Determination of raw part Raw part

Workpiece state before cutting

Main and sub-processes before cutting

Adjustment parameters before cutting

Interactions concerning raw part

Distortion concerning to raw part

Determination of process

sequence

Cutting processes

Interactions concerning processes

Distortion concerning processes

Selection of manufacturing

equipment

Manufacturing equipment

Interactions concerning equipment

Distortion concerning equipment

Determination of adjusting

parameters

Cutting parameters

Adjustment parameters after cutting

Interactions concerning parameters

Distortion concerning parameters

Workpiece state during cutting and after it

Main and sub-processes after cutting

Determination of target time Machines, tools etc.

Cutting Parameter

Table 1: Sorting findings to tasks areas

From Table 1 it is obvious that some categories are mentioned several times within the task

areas. This means that for example to get all information about recommendations for planning


the raw part several categories have to be taken account. To get all information nine categories

are suggested:

Main process (MP)

Raw part (RP)

Sub-Process (SP)

Manufacturing equipment (E)

Adjustment parameter (A)

Workpiece state (W)

Distortion (D)

Interaction (I)

Recommendation (R)

Steelmaking, forging, cutting and heat treatment are selected as main processes for a process

chain in steel production. The main processes can be divided in sub-process. With workpiece

state the state at a certain time in the process is meant. Interaction means the dependency of two

or more influencing factors on the process chain. The structure of the planning view is shown in

Figure 4.

Findings Process

chain

Material Geometry

Finding 1 1 SAE

52100

Cylindrical

ringFinding 2 1 SAE

52100

Cylindrical

ring

Main

process(MP)

Raw part

(RP)

Sub-

Process(SP)

Manufacturing

equipment (E)

Adjustment

parameter(A)

Workpiece

state (W)

Distortion

(D)

Interaction

(I)

Recommen-

dation (R)

MP1 RP1 SP1 - - - D1 I1 R1MP2 - SP2 E1 - W1 D2 - R2

Planning view

……

•Processchain 1

•Material

•Geometry

•Processchain 2

•Material

•Geometry

Finding1 Finding 2 Finding nR1 R2

MP RP SP E A W D I

User

Figure 4: Correlation between planning view, findings and recommendation

The aim of the user of the planning system is to look for recommendations out of the task areas

to create a process plan. For example to determine the process sequence of the main process

cutting (in Figure 4 maybe „MP1“) the planner can get all recommendations out of this category.

While maybe MP2 stands for the main process heat treatment the planner can also get all


recommendations of the following process and therefore he can adjust his cutting process by

considering the heat treatment process. The search for recommendations of other categories is

following the same pattern.

4 Structure of Knowledge and Planning System

From the previous discussed views all categories are known which have to be implemented in

the knowledge and planning system. Thereby both views have access to the findings. In the

following Figure 4 all views will be combined to the knowledge and planning system. Additional

the sources (S) of the findings will be added. To address the findings out of the views,

additionally tags (T) for each finding will be assigned.

User

Planning view

……

•Processchain 1

•Material

•Geometry

•Processchain 2

•Material

•Geometry

Finding1 Finding 2 Finding nR1 R2

MP RP SP E A W D I

Finding Tags

Finding 1 IF1

G1

MP1

RP1

SP1

D1

I1

Finding 2 IF2

MP2

SP2

E1

W1

D2

User

Knowledge view

IF M C G

S1 S2

Tags Tags

Figure 5: Sketchy view of the knowledge and planning system

In informatics so called tags are used for example to combine keywords with statements (here

the findings). The tags will be addressed by the categories. The principle will be shown by using

the knowledge view. The user is interested to know the findings of the category influencing

factors (IF) of the process chain of a cylindrical ring of the material SAE 52100. Displaying

findings IF1 and IF2 are realized by tagging the finding 1 with IF1 and finding 2 with IF2 (see

also the table in Figure 5). By clicking on this category the text of finding 1 and finding 2 will be

displayed. The same principle is effective for the planning view. As a difference to the

knowledge view, not the finding is important but the respective recommendation.

5 Examples

In this part two findings (see Table 2) out of knowledge view (see Table 3) and out of planning

view (see Table 4 and Table 5) will be exemplary presented. Whereat the findings are the same

in both views and related to process chain 1: SAE 52100, cylindrical ring. With the described

systematic the system can be established.


Nr. Finding Material Geometry Recommendation Source

1 “Fortunately, the through-hardening grade SAE 52100

seems not to need such a traceability regarding the results

of the Collaborative Research Center and some former

industrial work. Neither solidification cross section nor

position in the rolled bar were of any influence on the

resulting distortion of heat treated rings. But again, for

52100 no negative influence by lacking the exact position

information was observed.”

SAE

52100

Cylindrical

ring

For SAE 52100 neither

solidification cross section

nor the position in the

rolled bar should be

considered.

[Zoch

2009]

p. 346

2 „The changes of roundness of the quenched cylindrical

rings are influenced relevantly by the manufacturing

residual stresses. A change of the cutting parameters as

well as a change of the clamping conditions act very

sensitive on this resulted residual stress state. By the

following heat treatment these stresses will be released in

a complex way what on the other hand can influence the

resulted changes of roundness sustainably.”

SAE

52100

Cylindrical

ring

Take care of the influence

of cutting parameters and

the used clamping tool in

respect of the residual

stress state and the change

of roundness of cylindrical

rings.

[Clause

n et al.

2006]

p. 318

Table 2: Finding view, process chain 1

Nr. Finding Material Geometry Influencing

factor (IF)

Mechanism

(M)

Compen-

sation (C)

Generalization

(G)

Tag

1 See

Table 2

SAE

52100

Cylindrica

l ring

solidificati

on cross

section,

position in

the rolled

bar

- - for 52100 no

negative

influence by

lacking the exact

position

information was

observed

SAE 52100

Cylindrical ring

Cross section

Position

No negative influence

2 See

Table 2

SAE

52100

Cylindrica

l ring

Cutting

parameter

- - - SAE 52100

Cylindrical ring

Cutting parameters

Table 3: Knowledge view, process chain 1

Nr. Finding Material Geometry Main process

(MP)

Raw part (RP) Sub-

Process

(SP)

Manufacturing

equipment (E)

Adjustment

parameter

(A)

1 See

Table 2

SAE

52100

Cylindrical

ring

Steelmaking

Forging

Heat treatment

solidification

cross section

position in the

rolled bar

Rolling

Heat

treatment

- -

2 See

Table 2

SAE

52100

Cylindrical

ring

Cutting

Heat treatment

- Turning

Quenching

Clamping tool Cutting

parameter

Table 4: Planning view, process chain 1, part one


Workpiece state (W) Distortion (D) Interaction (I) Recommendation (R) Tags (T)

Through-hardening Distortion No marking for

active

compensation

necessary

For SAE 52100 neither

solidification cross section

nor the position in the

rolled bar should be

considered.

SAE 52100

Cylindrical ring

Steelmaking

Forging

Heat treatment

Cross section

Position

Bar

Rolling

Through-hardening

Distortion

Compensation

- Change of

roundness

- Take care of the influence

of cutting parameters and

the used clamping tool in

respect of the residual

stress state and the change

of roundness of

cylindrical rings.

SAE 52100

Cylindrical ring

Cutting

Heat treatment

Turning

Quenching

Clamping tool

Cutting parameter

Change of roundness

Table 5: Planning view, process chain 1, part two

6 Conclusion and outlook

Presented was a process-oriented knowledge and planning system for a structured depositing and

locating of findings along manufacturing processes for component distortion. The findings were

prescreened by process chain, material and geometry. With the help of two views (knowledge

and planning) the findings can be a basis of new experiments and they can also support a planner

to set up a process plan.

An evaluation of the findings by using e.g. rules is not necessary up to now. Most of the findings

are related very close to the process chain and there are still not so much generalized findings at

the moment. To fill up the system findings from literature were used. Basically it is also possible

to fill up the system immediately by experts when findings arise. Therefore, the findings can be

registered immediately after an experiment or the manufacturing of a product.

Acknowledgement

The work on this paper was accomplished within the Collaborative Research Center SFB 570 “Distortion

Engineering” at the University of Bremen. The authors acknowledge the financial support by the Deutsche

Forschungsgemeinschaft. Details on the SFB 570 can be found at the internet site (www.sfb570.uni-bremen.de).

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