Frequently Asked Questions
What materials can your products be supplied in?
We work with mild steel, stainless steel and aluminium, however, we are always happy to discuss any particular requirements a customer may have.
We are very conscious of our responsibilities to the environment and we insist that any timber used e.g. as with our Erskine seat ,comes from regenerated and sustainable sources. At present we use African Iroko and Red Meranti wood to meet all preservation issues.
Do your products come in standard sizes?
Whilst we have a “standard” stock range, all our products can be manufactured in any size to suit customer requirements. Names, logos, plaques, etc. can be used to customize any purchases.
Our Balmoral seat is a good example of our versatility with length, radius, shape, etc.
Galvanising - Why?
Hot-dip galvanising as a method of preventing corrosion of steel products was first introduced over 150 years ago to protect corrugated iron sheets. It has proven to be the most effective and reliable method available today. Its ability to grow in the face of more and more sophisticated competition is the result of the simplicity of the process.
Over the years David Ogilvie Engineering have tried some of the options available, but have always returned to hot-dip galvanising in the end.
Preparation
The galvanising reaction will only occur on a chemically clean surface, therefore most of the preparation work is done with this objective in mind. In common with most coating processes the secret to achieving a good quality coating lies in the preparation of the surface of the iron or steel. It is essential that this is free of dirt, grease and scale before galvanising. These types of contamination are removed by a variety of processes. Common practice is to degrease using an alkaline or acidic degreasing solution into which the component is dipped. The article is then rinsed in cold running water and then immersed into hydrochloric acid at an ambient temperature to remove dust and mill scale.
Welding slag, paint and heavy grease cannot be removed by the above cleaning steps and have to be removed before the work is sent to the galvaniser.
After a further rinsing operation, the components will then commonly undergo a fluxing procedure. This is normally applied by dipping in flux solution – usually about 30% zinc ammonium chloride at around 65-85°. Alternatively, some galvanising plants may operate using a flux blanket on top of a galvanising bath. The fluxing operation removes any last traces of oxides from the surface of the component and allows the molten zinc to wet the steel.
The Galvanising Process
When the clean iron or steel component is dipped into the molten zinc (which is commonly at around 450 degrees C) a series of zinc alloy layers are formed by a metallurgical reaction between the iron and the zinc.
The rate of reaction between steel and zinc is normally parabolic with time and so the initial rate of reaction is very rapid and considerable agitation can be seen in the zinc bath. The main thickness of coating is formed during this period. Subsequently, the reaction slows down and the coating thickness is not increased significantly, even if the article is in the bath for a longer period of time. A typical time of immersion is about four or five minutes, but it can be longer for heavy articles that have a high thermal inertia or where the zinc is required to penetrate internal spaces. Upon withdrawal from the galvanising bath, a layer of molten zinc will be taken out on top of the alloy layer. Often this cools to exhibit the bright shiny appearance associated with galvanised products.
Post galvanising treatment can include quenching in water or air cooling.
Conditions in the galvanising plant, such as temperature, humidity and air quality, do not affect the quality of the galvanised coating. By contrast, these are critically important for good quality painting, and in our own dedicated paint plant we can ensure the finished product is of a very high standard.
Quality
At David Ogilvie Engineering we are committed to ensuring quality management and manufacturing from the customers initial contact to final installation and beyond.
We have effective and established internal procedures throughout all elements of our processes, and we are currently working towards ISO 9001 accreditation.
Guarantees
We offer a lifetime guarantee on all our products against normal wear and tear.
Security and Fixings
Our products are manufactured with design and strength in mind. We work with our customers to establish the best method of ensuring the security of any purchase and to advise on the most effective ways to minimize vandalism and damage. Unfortunately no-one can offer a 100% guarantee against malicious destruction.
Limitations - Do we have any?
In our experience, there are none. If what the customer wants cannot be made to their exact specification we will say so, and then work to establish alternative solutions which suit the requirement and ensure customer satisfaction.