Posted 12th Nov 2014

In a different initiative for 2013, Nick Groom, managing director of Hertford-based precision turned parts subcontractor, Qualiturn Products, has taken the unusual step of advising manufacturers, designers and purchasers on the best way to source their components from outside suppliers.

Tips for designers

Product tolerances

Looking first at design, it is often the case that unnecessarily toleranced dimensions are specified on a drawing. Modern CAD software may default to very tight tolerances, typically ±10 microns, which are routinely applied to features on components even though they are not necessary for function.

Most features do not need to be anywhere near so precise, bearing in mind that an average human hair is large by comparison at 100 microns across. Stipulating very high accuracy increases not only manufacturing cost through having to reduce feeds and speeds, but raises the cost of inspection as well, as more frequent and time-consuming measurements have to be taken.

On the other hand, loosening tolerances around a drawing, consistent with maintaining component functionality, can greatly reduce the cost of manufacture and therefore the amount a customer is charged. It invariably also cuts lead-time from order to delivery.

Another tip is to design components wherever possible so that they can be manufactured efficiently from stock bar diameters, as this saves unnecessary cutting time.

Dangers of over-engineering

Qualiturn is proactive in providing advice on how to take further cost out of a part by reducing the amount of machining needed. For example, a geometrical feature can sometimes be modified to achieve material and time savings. Working with designer and customer to solve problems and make sure deigns can be made cost effectively, while still maintaining function, is an important role of the engineering staff at Hertford.

Drawings

Drawings should be clean and simple. Avoiding the use of yellow or other faint colours on drawings is beneficial, as they are difficult to read on hard copy printouts on the shop floor, which may result in errors and delayed production. When applying hidden detail lines, it is important to make sure that images do not become confusing, perhaps by adding another view or cross section.

Choosing the correct material

Material from which components are made can be changed to reduce manufacturing cost, according to Qualiturn's production director, Steve Aulton. For example, instead of using brass or steel, which are increasingly expensive these days, and then having the components plated, it is often cheaper to use stainless steels.

It is becoming more popular thanks to modern, effective methods of machining and welding it, and due to environmental concerns over plating. The use of stainless rose to over 50 per cent of throughput at Qualiturn during 2012.

Suppliers working together

When outsourcing the production of samples or new products, manufacturer's need to ensure that someone is contactable at their end to clarify any queries when a job is scheduled to run. This will allow any problems with the drawing or fit to be overcome quickly, ensuring delivery of a product that assembles perfectly and works as designed.

Tips for buyers

Order details

A buyer's order should be complete in all respects. It is surprising how often fundamental information is missing, like the quantity needed, delivery details and product issue numbers.

If there are any special requirements regarding cleanliness that are not printed on the drawing, Qualiturn needs to know this before quoting so that it can select the correct process for the parts in one of its industrial washing machines.

The time lag between submitting a quote and receiving an order can be long, yet often the parts are then needed 'yesterday'. Sometimes this is unavoidable, but if it can be prevented, the customer can save money by not having to pay a premium for a rush job. Undue haste in completing an order is sometimes the cause of things going wrong, which can delay delivery. The advice is: give the maximum amount of notice that is feasible for best results and lowest cost.

Packaging and shipping

The protection and handling of components during machining and transit will make a massive difference to the final look of a customer's components. Good storage conditions while they are on consignment stock at the subcontractor's premises will also help to maintain future deliveries of top quality products.

Collaboration is key

Nick Groom encourages customers to visit Qualiturn's factory on the Mead Lane Industrial Estate in Hertford as often as they like.

He said, "In practice, the companies we work for normally keep us at arm's length and rarely call in, but I think it is a missed opportunity. Manufacturers should work more closely with their suppliers to get the best out of them."

He explained that if a designer and perhaps a firm's quality manager sit around a table with Qualiturn staff, a resolution to problems and effective value engineering can be accomplished quickly.

If a buyer visits, he or she can witness the entire subcontract operation first hand and see machines turning out batches of simple to complex mill-turned components, 24/365, in batches ranging from 10-off to hundreds of thousands. The person will be in a better position to understand what makes the supplier tick and will be able to see how long it takes to set a CNC sliding-head or fixed-head lathe on the shop floor for a new batch run.

Back to Case Studies