PRODUCTION MANAGEMENT

Condition based factory planning

G. Schuh • A. Kampker • C. Wesch-Potente

Received: 30 April 2010 / Accepted: 15 October 2010 / Published online: 1 November 2010

� German Academic Society for Production Engineering (WGP) 2010

Abstract Consecutive planning approaches, common in

the theory of factory design today, fail to support planning

projects in practice. They neglect the interactions and

dynamics in the planning task and project as well as the

subjectivity introduced by the different stakeholders.

Unconsidered interactions, conflicting motives and inflexi-

ble project structure lead to time-consuming, expensive and

late adaptations. Local optimisation and deviations from the

overall objectives are consequences of insufficient syn-

chronisation and coordination. The approach proposed in

this paper strives for a paradigm shift from consecutive

processes to a modular, parallel approach, which can be

reconfigured according to the specific conditions of the

planning project and enterprise. This new approach inte-

grates the modularisation and configuration of the planning

process as well as aspects of management of instability and

second order observation. It has been successfully employed

in industry cases, which will be introduced in this paper.

Keywords Factory planning � Planning process �Modularisation � Configuration

1 Introduction

Today’s dilemma of factory planning is to design produc-

tion systems that, on one hand, last for decades but, on the

other hand, are adaptable to changing requirements of

the dynamic market environment. Furthermore, important

questions for process, resources and layout design can

often not be answered systematically due to uncertain

information and changes in requirements. Reliable prog-

noses are limited and planned flexibility increases the

required invest significantly. Therefore, several approaches

strive for a modular, reconfigurable production system to

cope with this discontinuity [1]. The continuous adapta-

tions to the dynamic requirements result in a growing

frequency of planning projects. While an average company

launches about one project per year, successful companies

realise twice as many projects in the same time [2]; thus the

acceptable duration of a project has decreased significantly.

Factory planning projects have to cope with an increasing

number of planning tasks and objects, needing to be inte-

grated into the planning scope whilst dealing with limited

information, resources and time. In addition to the external

dynamics, this demands for adaptations in the planning

sequence, parallelisation of planning tasks and redefinition

of interdependencies [1, 3].

Consecutive planning approaches, common in factory

design today, fail to support planning projects, which face

these dynamic conditions. They are characterized by

sequential, individual decisions that neglect the interac-

tions in the planning objects and in the stakeholders. The

fixed sequence does not meet the individual, enterprise

specific requirements of each project [3, 4].

Within the following paragraphs, the deficits of estab-

lished approaches of factory planning are discussed and a

new perspective of factory planning, named ‘‘Condition

Based Factory Planning’’ (CBFP) is presented.

2 New understanding of factory planning

As emphasised in the introduction factory planning is no

longer a task performed once in a decade or less. Modern

G. Schuh (&) � A. Kampker � C. Wesch-Potente

Laboratory for Machine Tools and Production Engineering

(WZL), RWTH Aachen University, Aachen, Germany

e-mail: G.Schuh@wzl.rwth-aachen.de

123

Prod. Eng. Res. Devel. (2011) 5:89–94

DOI 10.1007/s11740-010-0281-y

factories have to be designed to adapt to changing, situa-

tion specific requirements [5]. In consequence factory

planning needs to combine the initial factory design and

continuous reorganisation of the production system.

Approaches, aiming to support factory planning projects

under dynamic circumstances, have to understand factory

planning as factory development in order to adapt to

changing requirements that vary from company to com-

pany. Single planning projects have to be accelerated in

order to fit into the increasing planning frequency and the

overall factory development plan [4]. Furthermore, the

people that interact working in the factories as well as

planning factories have to be considered in the planning

approach: factory and project team are a social system and

have to be designed and managed as social system.

Challenges for factory planning projects are the there-

fore fast realisation in order to follow the external

dynamics, the adaptation to situation specific requirements

of different projects and the mastering of conflicting per-

spectives of stakeholders in social systems. These chal-

lenges are addressed in the following topics:

– standardisation and automation of factory planning,

– configuration of individual adaptive planning process,

and

– coordination of social systems

2.1 Standardisation and automation of factory planning

Common solutions to accelerate processes are standardi-

sation and automation. Especially the digital support of

factory planning projects is strongly driven by integrated

solutions standardising both functionalities of the tools

(e.g. interfaces, methods and tasks) and, in particular, the

processes in which those functionalities interact [6].

The application of digital tools in factory planning

projects is constantly growing; approximately 64% of the

projects use the support of design and simulation tools [7].

These systems are designed for experts. The user-interface

and the operating are adapted for trained specialists [8].

The majority of projects in small and medium companies is

realised by project teams that consist of ‘‘amateurs’’. In

addition to limited time, the involved planners have little

experience with available tools. Consequently, learning

effects are scarce and the usage of supporting systems is

limited to single applications or own solutions e.g. in

Microsoft Excel.

The increased (simple and intuitive) usability of plan-

ning tools is one important challenge in order to reach the

necessary degree of professionalisation of the planning

project and methodology, even in small projects [9].

Nevertheless a standardisation of interfaces, methods and

tasks in the process needs to be pushed.

2.2 Configuration of individual adaptive planning

process

The described standardisation and automation of integrated

software solutions (e.g. Siemens PLM and Delmia) leave

little freedom for individual processes [6]. Integrated

solutions are particularly designed for big companies with

own planning departments and experts. Consequently they

are everything but modular or interchangeable [9]. Espe-

cially small companies criticise the limited compatibility of

interfaces and possibilities to individually adapt the soft-

ware to their specific processes and requirements [4].

Consecutive approaches in factory planning cause sim-

ilar limitations concerning the adaptation of standard

planning process and methods to the individual require-

ments and specific processes of companies. External and

internal restrictions often force the project team to plan

parallel tasks that are supposed to be handled consecu-

tively. Information required for the planning is missing,

decisions are postponed and other planning tasks are

accelerated. Existing approaches offer no support for these

requirements [4]. The adaptive configuration of planning

processes and software solutions are additional challenges

for factory planning that seem to contradict the demand for

standardisation.

2.3 Coordination of social systems

Factory planning projects always change the existing

organisation, processes and structures of social systems.

E.g. due to the product oriented segmentation of production

former organisational structures and dependencies as well

as processes within the structures (e.g. order processing,

maintenance) are reorganised or completely new designed.

In this case the production systems as well as the project

team need to be understood as social systems [8]. Factory

planning can be understood as self-creation (autopoiesis) of

a social system; the project team (in particular the

employees and workers part of the future system) plans its

own social system (Fig. 1). Members of the existing system

are selected as part of the project team, which plans the

new production system during the planning process. The

ramp up begins with pilot projects that are rolled out to

the new system. The members of the project team are

(re-)embedded into the new system.

Characteristic for classical planning approaches are

coupled decisions that are made separately by individuals

or sub-teams [10]. Conflicting motives and backgrounds

lead to local optimisation of isolated planning tasks

regardless of the complete system [8, 11]. Experts,

including employees and workers part of the designed

system, are not being integrated into the planning process

early enough to benefit from their know-how [8]. Main

90 Prod. Eng. Res. Devel. (2011) 5:89–94

123

challenges concerning the social system aspects of the

planning are the integration of the relevant stakeholders

and project members as well as their synchronisation in the

project progress.

3 Condition based factory planning

Condition Based Factory Planning (CBFP) describes a

modular, parallel approach, which can be reconfigured

according to the specific conditions both of the planning

project and of the company. In the following, three main

aspects of CBFP are presented.

The modularisation allows the standardisation of the

planning content (methods, tools, etc.) within planning

modules. These modules encapsulate the planning content

following the object oriented approach known from soft-

ware development [1]. Interconnections between modules

concerning input information from other modules and

results used by other modules are defined by interfaces.

This is the basis for the individual configuration of the

modules to a planning process that can be reconfigured

during the project adapting to changes in surrounding

conditions. In the same way the project team has to be set

up in sub-teams that plan the modules. By observation of

deviations of the project progress and changes in require-

ments, the occurring instabilities can be managed by

reconfiguration, negotiation, escalation and intervention.

3.1 Modularisation of the project

The planning task, team and software are modularised

based on the object oriented principles introduced by

Schuh for the modelling of production systems [1]. The

task-related encapsulation of methods and tools (e.g. for

planning of capacity, assembly processes or material sup-

ply) into modules allow the reduction of interdependencies

on defined interfaces. The standardisation concerning

methods and tools is encapsulated in the modules, which

can be combined according to the specific requirements of

the project. Changes in requirements have a defined

influence specified by the in- and output relations of each

module [1].

The CBFP approach is based on a framework consisting

of 28 basic modules and eight planning domains, which are

defined based on project experience of the Laboratory for

Machine Tools and Production Engineering (WZL). The

modules accomplish different planning duties like: capac-

ity planning, segmentation or workstation design. Figure 2

shows planning modules for material supply and assembly

process as well as the necessary planning information

‘‘input’’ and the results ‘‘output’’ of the planning module.

The planning-domains represent the involved disciplines

(stakeholders) in the project, like production process,

resource planning or logistics. Additionally, support-

domains, like ramp up and project management or digital

factory are established to control, (re-) configure and assist

the planning-domains. A planning-module can be executed

repeatedly in different levels of detail. That means that at

the beginning of the process a rough corridor for the nec-

essary capacity is planned, and then be specified within

consecutive iterations. The sequence of the modules in the

iterations are reconfigured and adapted during the project

[3].

In analogy to the object oriented modularisation of the

planning object [1] and the task, the planning team can be

divided into sub-teams with regard to the existing inter-

dependencies to improve the controllability of the teams

and their collaboration. The set up of the sub-team is

described in the following chapter.

The approach is complemented by a modularisation

concept for the software support. For the outlined dilemma

between standardisation and adaptiveness, especially small

and medium sized companies demand simple and intuitive

software solutions that can be adapted to their specific

Pilot Project

Existing Production System

Planning Team

Autopoiesis

New Production System

Planning Process

Fig. 1 Factory planning as self-creation of social systems

Material-supply

AssemblyProcess

Buffer number

Supply type

Supply lot size

Supply frequency

Buffer levels

Process times

Process chain

Variants tree

Replenishment time

Material cost

Service level

Production program

Set-up costs

CAD drawing

St. process chain

Resource structure

Features tree

Product structure

Customer tact

Input Planning Modul Output

Fig. 2 Planning modules for material supply and assembly process

Prod. Eng. Res. Devel. (2011) 5:89–94 91

123

needs. WZL has developed several small tools (e.g. for

layout planning, segmentation, levelling, production con-

trol) that function as add-in in commonly used software

suits, like Powerpoint, Excel etc. or as web-based solution

[9]. Figure 3 shows screenshots of these tools. One of the

major problems resulting from modularisation and decen-

tralisation is the appropriate configuration of the planning

modules and structural bonding of their interconnectivity

and the synchronisation of the collaboration in the project

team, described in the following paragraphs.

3.2 Configuration

The described planning modules have to be combined and

configured in order to accomplish a company and project

specific planning process. In a first step the planning scope

and specific (additional) interdependencies have to be

defined. Based on these restrictions the relevant modules

for the project are selected, dimensioned and specified

regarding applied methods and tools (Fig. 4). If the project

focuses on the reorganisation of an assembly workstation in

an existing building, modules that do not correlate with this

planning scope (e.g. building planning) can be skipped.

The planning sequence depends on the existing input

information and restrictions as well as the necessity of

decisions. Adaptations in the sequence can be realised by

reconfiguration of the modules, which encapsulate the

planning content. Circular dependencies are dissolved by

setting initial values and corridors which are specified

within consecutive iterations. This allows the parallel

planning of modules that circularly depend on each other as

well as changes in the planning sequence. In order to

coordinate the collaboration between the modules, thresh-

olds for specific parameters (e.g. the maximal cost or size

of a planning object) and the available degree of freedom

for results of each module have to be defined regarding the

interdependencies of the involved modules. Thus, potential

conflicts can be identified in the course of planning and

negotiated or escalated to the appropriate decision level. In

this way the structural interconnectivity of the planning

content is defined and thus the information exchange

between the modules. The scheduling of milestones

according to decision and synchronisation points sets the

time framework for the project. The resulting phases define

the tact of the project representing the quotient of project

duration and the number of decisions. The planning-mod-

ules are aligned within iteration cycles with defined results

for the milestones. Figure 5 shows the described perspec-

tive of the CBFP-Process over time.

Corresponding to the selected modules and domains, the

planning team is composed matching competences and

roles of the team members with the requirements of the

modules and the schedule. An important task is the

capacity planning according to the available time between

the milestones and the configuration of the iterations. Using

Segmentation Assembly Levelling

Layout.ppt Production Control

Fig. 3 Intuitive tools for segmentation, levelling, layout planning and

configuration of production control

Fig. 4 Interconnectivity of planning modules and configuration

t

ME

Production Control

Ramp UpProject Management

Pla

nnin

gD

omai

ns

Structure

LogisticsResources

Layout

Capacity

Production Process

Target and Restrictions

Decision Points

Initial Value

new

planned

Moduls LevellingTakt

Fig. 5 Synchronisation and reconfiguration of the planning process

over time

92 Prod. Eng. Res. Devel. (2011) 5:89–94

123

a revised capacity curve, based on the hyperbola of Bul-

linger [12], inefficiencies in the project team are considered

in the capacity planning. The revised capacity curve

(Fig. 6) is applied to estimate the required capacity for the

execution of the modules within iterations and the best size

for the sub-teams that work on the modules. On this basis

the project team is composed and dimensioned, considering

the number of interfaces and the complexity of coordina-

tion as well as the number of parallel tasks. Special

attention has to be paid to integrate the relevant experts and

their know-how and perspectives into the planning. This

allows considering and avoiding possible obstacles and

increasing the acceptance of decisions as well as negoti-

ating conflicts well-foundedly [10].

The CBFP Platform for the digital support is configured

and reconfigured according to the demands of the selected

planning modules and the capabilities of the involved

planners and existing infrastructure [9]. The standardised

interfaces of the tools developed by WZL ensure the

compatibility of results and data. The following paragraph

describes how the synchronisation and the reconfiguration

of the planning course is realised.

3.3 Management of instability by observation

The individual configuration and the set-up of the structural

interconnectivity is the basis to react to external require-

ments and targets as well as internal conditions. In the

course of the project, this initial configuration has to be

adapted or even radically reconfigured to meet the dynamic

of the circumstances. In consequence, modules can be

relocated or repeated because of new and changed infor-

mation and requirements. In the same way, the composition

of the project team has to be adjusted to correlate with the

capacity and competence needed for the modules.

According to the principles of second order observation

[13, 14], the project is monitored to identify deviations,

conflicts and local optimisation. Analogue to the method of

Statistic Process Control [15], the thresholds and degrees of

freedom for the planning results need to be controlled and

if needed reconfigured. A virtual control room (c.f. oper-

ations room of Beer [16]) is integrated into the CBFP

Platform to handle the various information concerning the

performance and progress of the planning modules. Con-

flicts between modules and changes in input-information

can be visualised using network diagrams and schedules.

The user interface can be configured according to the user

and his position and information demand. In case of per-

ceptible deviations that interact with other modules speci-

fied mechanisms work on the different levels of conflict.

On the planning level conflicts need to be negotiated in

order to find joint solutions broadly accepted by the

stakeholders and to avoid local optimisation [10]. Using the

Mechanism Design theory of Hurwitz [17], mechanisms to

negotiate the major conflicts in factory planning are

developed. These conflicts concern the allocation of space,

invest, personnel and resources. If conflicts can not be

negotiated, they need to be escalated to the next decision

level.

In addition to escalating decisions concerning conflicts

between planning modules, this level (e.g. project man-

ager) has to observe changes and instability in require-

ments that influence the planning and intervene if

necessary to initiate reconfigurations of the project struc-

ture (structural interconnectivity or schedule), the project

team or the software support [18].

4 Industry case: design of an assembly system

In order to illustrate the practical relevance and potentials

of Condition Based Factory Planning, a representative

planning project of WZL and an industrial partner is pre-

sented. The project focuses the design of the assembly

system and logistics for a new generation of control cabi-

nets which are developed parallel. The assembly unit is to

be situated in the existing buildings.

The initial project set-up was configured according to

the requirements (forecasted quantity, product specifics,

variants, available space etc.) and capabilities (available

project team, software tools, etc.) of the company and

WZL. Modules for the planning domains capacity, struc-

ture, production process, logistics, resources and layout

were selected and the required information checked. New

modules for the domains product and technology were

added and interconnected with the existing to consider the

parallel product development process. Within the project

duration several changes in the requirements and in the

composition and size of the project team evolved, which

resulted in changes in the sequence of the planning.

0 50 100 150 200 250 3000

5

10

15

20

25

Project duration in days

Num

ber

proj

ect m

embe

rsIdeal capacity hyperbola

Capacity with respect to inefficiencies caused by:

- Number of parallel problems/ tasks

- Communication losses at interfaces

Fig. 6 Capacity curve for the set up of the project team

Prod. Eng. Res. Devel. (2011) 5:89–94 93

123

Due to the encapsulation of the planning modules and

the defined interdependencies significant changes could be

handled fast and with consideration of consequences and

side effects. The reduction of the forecasted production

quantity by 30% resulted in the quick re-planning of the

production programme and the selective adaptation of the

assembly and the logistic system. The consequences of

the marketing driven increase of variants (46%) on the

assembly system (form of segmentation, number of work-

stations, cycle time, invest, etc.) could be illustrated and

escalated to the decision level (plant manager) on this

basis. Additional product specifics resulting from more

severe testing and security requirements led to new

assembly content, which was analysed and specified with

assembly workers integrated in the project team.

Conflicts concerning the available space for different

preassembly areas were negotiated with the affected par-

ties. During the project, several similar changes of

requirements (e.g. concerning testing procedures and ramp

up locations) as well as demand of synchronisation (e.g.

coordination of product changes and adaptations of the

assembly process) could be facilitated by the consequent

application of the principles of modularisation and defined

interdependencies, and interfaces. Altogether, the project

duration was reduced by 60% compared to the preceding

product launch with a similar dimension.

5 Summary

The dynamic environment of production systems demands

a new understanding of factory planning as factory devel-

opment. CBFP is a new approach to cope with the resulting

challenges. The paper introduces three main aspects of

CBFP:

– modularisation,

– configuration and structural interconnectivity, and

– management of instability by observation.

The modularisation of the planning content, software and

project team is based on the principles of object orientation

and is precondition for the configuration of the planning

project. The management of instability by observation

secures the synchronisation of the decentralised planning

and reconfiguration of the planning project.

While consecutive approaches and integrated IT-Solu-

tions, common in factory planning today limit the indi-

vidual adaptation of the planning process to the specific

requirements of companies and projects, the proposed

approach is to optimise the adaptiveness of the process.

First applications in industrial case-studies have verified

the relevance and potentials of the addressed issues. While

to a large extent the individual components of the solution

are known from various disciplines, their combination

discloses a number of questions which are being investi-

gated in ongoing research.

Acknowledgments The new approach of CBFP is being investi-

gated by the Laboratory of Machine Tools and Production Engi-

neering (WZL) within two publicly funded research and development

projects (German Research Foundation, DFG): the ‘‘Cluster of

Excellence–Integrative Production Technology for High Wage

Countries’’ and the Graduiertenkolleg 1491/1 (University graduate

training programme) ‘‘Interdisciplinary Ramp-Up’’.

References

1. Schuh G, Bergholz M (2003) Collaborative production on the

basis of object oriented software engineering principles. Ann

CIRP 52(1):393–396

2. Schuh G, Ripp S (2003) Survey smart factory. WZL RWTH

Aachen

3. Schuh G, Wesch C, Gottschalk S, Gulden A, Koch S (2007)

Object-oriented factory planning—Architecture and procedure.

wt Werkstattstechnik online 1–2:166–169

4. Schuh G, Franzkoch B, Burggraf P, Nocker J, Wesch-Potente C

(2009) Configurable planning processes for factory planning.

wt Werkstattechnik online 4:193–198

5. Schuh G, Gottschalk S (2008) Production engineering for self-

organizing complex systems. Prod Eng Res Dev 2:431–435

6. Milberg J, Neise P (2006) Organizational design of supply chains.

Prod Eng XIII/ 2:181–186

7. Straßburger S, Seidel H, Schady R, Masik S (2006) Werkzeuge

und Trends der digitalen Fabrikplanung. Tagungsband zur 12.

Fachtagung, Kassel, 26–27, Sept 2006, 391–402

8. Schuh G, Gottschalk S, Wesch C (2007) Potentials in Computer-

aided Factory Design–Negotiation-based Top-down-Bottom-Up

Approach. Computer-Aided Production Engineering (CAPE),

Conference Proceedings, pp 43–52

9. Schuh G, Gottschalk S, Nocker J, Wesch-Potente C (2008)

Flexible Interconnectivity vs. proprietary Integration. wt Werk-

stattechnik online 3:127–131

10. Lu SC-Y, Elmaraghy W, Schuh G, Wilhelm R (2007) A Scien-

tific foundation of collaborative engineering. Ann CIRP

56(2):605–634

11. Simon HA (1996) The sciences of the artificial. MIT Press,

Cambridge

12. Bullinger H-J (1995) Arbeitsplatzgestaltung. Teubner, Stuttgart

13. Von Foerster H (1982) Observing systems. Intersystems, Salinas

14. Schmidt S (2005) Unternehmenskultur: Die Grundlage fur den

wirtschaftlichen Erfolg von Unternehmen. Velbruck, Weilerswist

15. Pfeifer T (2001) Fertigungsmesstechnik. Oldenbourg, Munchen,

pp 359–376

16. Beer AS (1995) Brain of the firm. Wiley John and Sons Inc.,

New York

17. Hurwitz L, Reiter S (2006) Designing economic mechanisms.

Cambridge University Press, New York

18. Kruse P (2009) Next practice. Gabal, Offenbach

94 Prod. Eng. Res. Devel. (2011) 5:89–94

123