Producing cost effective coil wound components

The design and manufacture of coil wound components is a specialised task, argues Ralph Gordon, Director and General Manager of North Devon Electronics.

As systems designs and manufacturers of electromechanical components increasingly look to outside help in the design, manufacture and supply of coil wound components it is important to take the correct steps at an early stage to achieve optimum results in terms of product design, performance, life, costs and delivery.

The first and most important step is to talk as early as possible about any planned product.

First, let us clarify the term "coil wound component".

For the purposes of this article we are confining our thoughts to inductive coil wound components, applicable to their use in electro-mechanical components.

An inductive coil wound component is essentially a conductor wrapped around a self supporting plastic former with or without an integral magnetic medium.

Coil wound components can be made in any size from a micro device the size of a pin head to a distribution transformer the size of a room.

It is therefore important to seek the help of a manufacturer with experience in the coil wound technology applicable to the size or sophistication of one's product and application.

Some companies may have the design skills but lack the manufacturing capability.

Many companies do have the resources to carry out their own in house coil winding and will continue to do so.

However there is a growing trend toward outsourcing.

The benefits of this are the removal of administration and production costs and the achievement of scheduled just-in-time deliveries.

A specialist also brings many years of coil winding designs and manufacturing experience into the design and manufacturing process.

One cannot overstate the importance to meet and to talk at the earliest possible moment - even at the "concept" of the design of a product.

Total confidentiality agreements apply and the benefits are substantial.

From our experience, informal discussions have on occasions led to a 20% reduction in overall costs before a prototype has even been produced.

At a first meeting it is to everyone's advantage that as much information can be presented as possible.

The physical and performance parameters of the component will dictate or influence decisions to be made on design, materials, construction and ultimate costs.

How a coil wound component is to be installed during production can also affect design considerations.

Apart from a briefing on specifics it is also useful to hold "open" discussions and even apply lateral thinking as this can occasionally result in a completely new approach to the design of the final product.

One of the most basic considerations is the choice of materials.

For the main conductor the usual material is copper in round or rectangular profile or in the form of flat copper foil.

Base copper is insulated with different types of enamel in various grades to meet specific temperature needs - usually between 105 and 200C.

Various types of magnetic material can be added to the construction of a coil wound component to improve its performance.

These include steel for low frequency applications and ferrite for higher frequency applications.

The shape and size of any magnetic material used will depend on performance requirements.

It is vital to identify the most suitable materials for any coil wound component.

The sourcing of moulded plastic formers also requires special care as many suppliers of moulded plastic products don not have the experience necessary to produce a plastics component that will allow high production run trouble free winding.

Before there is any commitment to approving a long production run for any component one must establish that it meets the demands of modern manufacturing and production line techniques.

It is therefore very advisable to produce small quantities from prototype tooling before commitments to investing large sums of money.

Samples can be produced through soft tooling, fabricated bobbins, SLRs and hand winding.

Once approval has been granted and a production schedule agreed standard coil winding machines usually cover normal applications.

However, machine customising may be required to produce specialist components - particularly where long runs are scheduled.

Customising of production machinery is only carried out once a design has been proven and an order placed.

At the other end of the scale some special miniature coil wound components may or can only be produced through "hand" winding.

Hand winding does not however compromise quality in any way.

Coil winding technology is constantly changing and to keep pace with the advances in coil winding, specialist coil winding companies need to invest and continually update their production capability to maintain quality control and meet scheduled delivery promises.

For very long runs reaching into millions, automation is the answer and it's in this area that the specialist company comes to the aid of customers with a need for very high production throughput and just-in-time delivery.

Such automated coil winding machinery is designed to operate 24 hours a day - 7 days a week.

To guarantee optimum quality control all coil wound components designed, manufactured by an outside source must be supplied by companies with ISO9002 approval - it is a customer's guarantee of quality control.

The supply of wire wound components is usually geared to the demands of a customer's production line.

A supplier has to be flexible in their delivery service and must be able to offer customers "just-in-time", daily deliveries, Kanban systems, buffer stocks, self-billing and ship to stock arrangements.

Systems designers and manufacturers of OEM products will obviously be aware of their need for wire-wound components.

What they may not be aware of is the wide experience and areas of specialisation available from established independent suppliers of coil wound components.

As an example, our own areas of experience includes engines, colour televisions, automotive, consumer OEM and defence using coil wound component from subminiature to 100VA transformers.

The preparation of essential data, early discussion and the presentation of a detailed questionnaire will help considerably in reducing the time from concept to production, overall costs and the delivery of a long life component.

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