Integrated CAD/ERP framework for modular construction industrialization through lean manufacturing concepts.

Zahharov, Roman ; Shevtshenko, Eduard ; Karaulova, Tatyana 等

1. INTRODUCTION AND BACKGROUND

1.1 Modular Construction

The modular buildings are sectional prefabricated buildings that are manufactured at off-site plant. Modular concept offers improved cost effectiveness and favourable project economy compared to conventional alternatives. In conventional construction, a general contractor has to rely on various local construction companies with limited experiences for complex projects. This invariably causes extra costs and delays. In current case study most of the construction work is performed at indoor production site, with rational and effective working procedures. Engineering, procurement and construction (EPC) are the functions of one company, which results in much higher operational efficiency, compared to the typical EPC partner companies that do not have common information platform.

1.2 The Lean Manufacturing and Lean Construction

Most of the research in partnering and lean construction primarily focuses on the useful elements within partnering and lean construction respectively. For instance (Josephson & Saukkoriipi, 2005), studied the sloppiness, waste and non-value adding activities in constructions. They wrote that in total construction costs can be reduced that up to 50% simply by focussing on the construction company's core business. Their research shows that approximately 45% of all construction work on a Swedish construction site is categorized as indirect work such as handling of materials and planning, 35% is categorized as interruption in work as well as waiting and unexploited time and only 20% is categorized as direct work, which directly generates value for the project, company, and client. All the above mentioned figures are related to the workmanship. Authors states that more than 10% of the total construction costs and time spent on the construction projects is spent on materials or machinery waiting. It often results in extra planning and controlling activities, which does not create any value to the project. Thus waste can be minimised and the construction process should be as lean as possible (Ricciuti, 1992).

2. INTEGRATION OF CAD AND ERP SYSTEMS

As a result of the research authors propose a framework for CAD/ERP integration via a central database (Fig. 1).

[FIGURE 1 OMITTED]

At the beginning of the project, the Bill of Material (BOM) structure is transferred from a CAD system to a central database. The central database includes all manufacturing operations required for a particular project. The technological relation is added to every operation, which requires the materials. Then the items with technological relations are transferred to the ERP system where the manufacturing planning of projects is performed. Master Planning and Scheduling (MPS) engine enables to plan the start and the end of every operation, and the MRP engine ensures that every operation is covered by materials or triggers alarm to production planners in case if material would not be unavailable at required production date (Little & Yusuf, 1995).

3. APPLICATION OF DEVELOPED FRAMEWORK AT "PHARMADULE" ENTERPRISE

Author implemented a prototype of the new CAD/ERP integrated model. The product data management system (PDMS) manages the CAD data for engineering design. An ERP system Movex manages the production data. In-house developed central database DePlan is used to build the connection between PDMS and Movex. The internal constraints for planning are production resources and components are taken into account. High-level project plan, coordinated by the customer, acts as an external constraint for production, which sets time limits for manufacturing and specific milestones.

Traditionally the demand is generated by the ERP system accordingly to the BOM of product structure. But with strict Engineering to Order (ETO) oriented design, where every single module is different ,and with batch to batch engineering data release schedule the ERP system is not able to control the material requirements. There is simply no input for MRP engine as there is no product structure. In such case a BOM has to be transferred batch by batch directly to manufacturing orders. When a design for the first batch (several modules) is finalized, quantities of components are sent from CAD to DePlan and further to ERP system. A MRP engine in ERP system will calculate dates for materials request accordingly to the production plan of manufacturing orders.

As a result, the whole chain a very strict push system. In an integrated system, a pull material handling strategy is combined into the traditional push system. A material classification chart is developed to identify pull materials. Due to the flexibility of DePlan and the full support of pull materials handing by Movex pull materials are excluded from BOM in DePlan and Movex.

3.1 Production Analyses

In case study production was mostly disrupted by component delivery delays and the absence of related information. Material delays resulted in additional working hours of constructors, planners and labour: frequent changes of operations within one module, working on several modules, working on operation with lower or higher resources than optimal (Fig. 2).

[FIGURE 2 OMITTED]

All those disturbances of workflow are the result of replanning in "do-what-you-can-where-you-can". So the durations of manufacturing operations are extended and consumption of resources is increased. Efficiency decreases drastically.

3.1 Implementation of Lean Manufacturing Concepts

After the implementation of lean manufacturing concepts the production through put time was decreased by 45% (Fig. 3). (Orlicky, 1975; Lee, 1993)

[FIGURE 3 OMITTED]

TPT = ProductionHoursPerModule-PrefabricationActivities/WorkersPeModule *Noshifts * ManHoursPerWeek (1)

Where:

ProductionHoursPerModule = Sum of man-hours activities that

lay on module critical path; PrefabricatioActivities = activities that do not lay on critical path;

WorkersPerModule = average amount of workers that can work simultaneously in one module, without decrease of efficiency;

NoShifts = working shifts in production;

ManHoursPerWeek = Sum of hours for that worker can produce during one week with one shift planning.

PlanYearly Capacity = WeeksPerYe ar/TPTweeks * ModulePlac es (2)

Where:

PlantYearlyCapacity = Amount of modules that can be manufactured within period of one year with specific TPT;

WeeksPerYear = working weeks during one year without

holidays, considered as 50;

TPTweeks = Through Put Time in weeks;

ModulePlaces = maximum amount of modules that can be manufacturing simultaneously within given production plant.

4. CONCLUSION

The developed modular concept is much more efficient than conventional construction projects for pharmaceutical industry. The efficiency of modular construction was improved after the implementation of integrated CAD and ERP framework, that unites engineering, procurement and production into one seamless organization. The real time information about materials is available to all parties. In the construction field, where project organization is scattered with barriers between different subcontractor companies (engineering, procurement and construction), such tight integration would be impossible.

Before the integration of CAD and ERP Pharmadule has implemented pull material handling strategies (Kanban) for bulk material. After the push system was implemented for project unique and standard materials, organization has achieved an implementation of hybrid push/pull material handling methods. Hybrid just-in-time (JIT) philosophies allowed both flexibility and control of material flow at the same time. The efficiency of the working process and organization has been smoothed and formalized. Production has eliminated existed material delays and optimized resource usage. The risks of project delay are minimized, and time to market will be decreased in future. The strategic goal is achieved. The Pharmadule's is the fastest supplier of manufacturing facilities for pharmaceutical and biotech industry.

5. ACKNOWLEDGEMENTS

Hereby we would like to thank the Estonian Ministry of Education and Research for targeted financing scheme SF0140113Bs08 that enabled us to carry out this work

6. REFERENCES

Josephson, P.; Saukkoriipi, L. (2005). Waste in Construction Projects--Need of a Changed View (In Swedish). Fouvast, report 0507, Goteborg

Lee, C.Y. (1993). A recent development of the integrated manucacturing system: a hybrid of MRP and JIT. International Journal of Operations & Production Management, Vol.13, No.4, pp. 3-17, ISSN 0144-3577

Little, D.; Yusuf, Y. (1995). Extension of MRPII systems to meet future business, Proceedings of of the Eleventh National Conference on Advances in Production Research, D.Stockton (Ed.)pp. 14-17, ISBN-13 978-0748404001, DeMontfort University, September 1995, TJ Press, Padstow

Orlicky, J. (1975). Materials Requirements Planning, McGraw Hill, ISBN 0-07-050459-0, New York

Ricciuti, M. (1992). Connect manufacturing to the enterprise (software). Datamation. Vol. 38, No. 2, pp. 42-44. ISSN 10628363