Eco-efficiency of the cold roll formed product supply chain

Abstract

Recently there has been a move towards environmentally conscious manufacturing with an emphasis on life-cycle assessment. The intention is that life-cycle assessment be integrated into a holistic or systemic approach to product design. Such an approach allows consideration of the total energy expended, the resources used, and the waste created. Hence, enabling the entire environmental impact to be determined and minimised. Hadley Industries PLC [1] is a master in utilising the cold roll forming process to produce an increasingly wide range of products. The question considered in this paper is how a cold roll forming company mid-way along the value adding chain, a sub-contractor, not involved in final product designs and hence product life-cycle assessments can ensure they are a sustainable and environmentally conscious manufacturer.

Introduction

Cold roll formed products are predominantly produced from steel in the strip form which is produced in large coils. Hot rolled steel coil can be directly cold roll formed, however many post processes are often required to produce coil to higher specifications before it is cold roll formed. The most common of these include: pickling, cold rolling, annealing, galvanising and coating. Once the coil has been processed, it is transported to another facility which stock holds the large steel coils and cuts them into the widths required by customers.

In roll forming the coil is passed through a series of forming tools to achieve the desired profile. The cold roll formed products are cut to length and the majority are distributed to the construction industry, which may supply, or be themselves, the end user of the product. Typically, the useful lifetime of construction steel products ranges from 10 to 60 years [2] depending on their application, during which time a small percentage may be reused for additional applications, e.g. reclamation from construction uses. After its useful life the rolled section may be dismantled from its application and sent for processing and recycling, or sent to land fill. In the UK around 60% of scrapped steel is recycled [3]. The fundamental product, energy and waste flows of this supply chain are illustrated in Fig. 1.

Life-cycle assessment of steel products shows that the production of 1 tonne of steel from raw materials and scrap results in emission of between 1.6 and 2.4 tonnes of CO₂ to the atmosphere (depending on the production process used) [4], [5]. According to the International Iron and Steel Institute the resulting CO₂ emissions from the production of steel are primarily due to the energy requirements in reducing iron ore [5]. As part of its long term commitment to sustainability, the major world steel industries are seeking to reduce greenhouse gasses by continuing to increase efficiency of the steel production process as well as encouraging innovation in product design. Every agent that plays a role in the steel supply chain needs to take on this initiative by producing in a more eco-efficient and sustainable fashion.

Cold roll forming is just one of the many processes identified in the supply chain system of steel products which adds value to flat steel coil, the process input, and provides cold roll formed products, the process output, to other industries. The agents of such a system are considered to be intermediate process providers (IPP), and the roll forming process; an intermediate unit processes (IUP). It has been shown that such IUPs can greatly affect the life-cycle of the final product [6], even if alone they do not constitute a significant impact of the complete system. It also follows that if all intermediate unit processes are made to be more efficient, by minimising waste and optimising processes, the demand for the input materials in each case will be less, thus the initial demand for raw materials and the consequential environmental burdens which arise from the initial processes can be reduced.

It should therefore be considered the responsibility of each IPP to minimise the environmental impacts within its own control by minimising waste, instigating prudent use of natural resources and by designing products in a more eco-efficient manner, to ensure that the accumulation of total impacts along the supply chain are reduced.