AW Fraser Blog

Vertical Brass Extrusion Press Great for Hollow Brass Rod

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Vertical Brass Extrusion Press Great for Hollow Brass Rod

September 17, 2011 Uncategorized by Matt Toohey Edit

The Extrusion Press at AW Fraser is an indirect vertical press with a maximum billet weight of 37 kg. It was manufactured by Fielding & Platt of Gloucester England and has had many improvements made to it during the years it has been in operation at AW Fraser Ltd. These improvements which involve nearly every component of the Press with the exception of the rams, have enabled even greater accuracy than the original design. The extrusion staff also have many years' experience in the operation of the press and a good understanding of the capacity and capability of the department.

We do not use bridge-type dies in the manufacture of Brass Extrusion, so our material does not suffer any potential quality issued created by that process. It also means we can offer a wide range of hollow brass extruded alloys which are beyond the technique of the Bridge-type die. We can make C46400 and C67300 Brass Extrusion with variable wall thickness and excellent concentricity. It also enables us to be very competitive in brass machined components manufactured in our own machine shop.

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Bronze-Web-based-ordering

July 21, 2011 Uncategorized by Matt Toohey Edit

We are planning to introduce a web-based ordering system in the coming months. The reason for this is that we want to be accessible to our clients in their time zone and to further automate our service and thereby reduce any opportunity for error.

Initially, we are planning to offer the service to our bronze distributors in our home market. This is so we can be on hand to fine tune the service once it starts and help get the service to its optimum performance. Then after we have completed the fine-tuning, we will roll it out customer-by-customer to the rest of our client base.

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Bronze Alloy Material Substituion

June 02, 2011 Uncategorized by Matt Toohey Edit

One of the key engineering challenges we face in modern manufacturing is choosing the right materials for our products to ensure maximum product life at the most appropriate cost to our market segment. This is as true for bronze and brass alloys as it is for the other components in any product and we often get asked by our customers for help with their material selection. The key mechanical considerations when choosing the correct bronze alloy are the ultimate tensile strength, the yield strength, the elongation and the hardness, while consideration may need to be given to the shear strength, compressive strength and maximum and minimum operating temperatures, as with any metal.

The best way to describe the ultimate tensile and yield strength measures in terms of a ductile material such as a bronze alloy, is as a measure of how much force a material will withstand before it deforms in a plastic manner (yield) and ultimately "necks" or loses cross-sectional area due to the plasticisation of the test specimen (ultimate tensile). Eventually the specimen will break.

Bronze Tolerances and Machining Allowance

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Bronze Tolerances and Machining Allowance

September 29, 2010 Uncategorized by Matt Toohey Edit

Bronze foundries around the world use different tolerance / machining allowances to enable their customers to plan to use the minimum machining possible to create their part from cast bronze bar. Less machining means less time and also less chip or swarf left over at the end of the process. Here at AW Fraser we have our own machine shop, so the feedback between the foundry operation and the machine shop is a tight loop. This means that we are always trying to improve our cast bronze product and under our lean manufacturing projects we are looking to take cost out of the process and as a result our cast bronze customers benefit from good quality bar. At AW Fraser we combine the tolerance and machining allowance and add it on to the nominal size so that if you order a particular size, the bar should clean up to the size you have ordered.

The process of bronze continuous casting involves the transfer of molten bronze from an induction furnace via a crucible to a heated casting pot which has a die mounted to it. The die design determines the shape and size of the finished bar. The die is cooled to enable the bronze to form the desired shape. The cooling process means that the bronze bar will shrink as it cools. The bar is extracted from the casting pot by a set of rollers or jaws and the speed of extraction is a factor in the rate of cooling and this affects the final physical properties of the bar. The die itself is manufactured on-site from carbon and this material provides excellent non-friction properties meaning the bronze is unlikely to freeze or get stuck in the die. However the carbon does wear and so the size of the die will change over time. There are also small variations in size caused by the exact chemistry of the bronze and the exact temperature of the metal when it is poured from the crucible into the casting pot. A further factor to consider is that the bronze continuous casting method does produce slight variations in size as it pulls the bar from the machine. A further consideration is that some alloys, particularly aluminum bronze and manganese bronze have small surface cracking as a result of the casting process. This is normal and we have a different tolerance/machining allowance table to allow for this property. To allow for these small variations in size we have what we call the bar tolerance which is what we allow our production people to manufacture within. For example, let us look at 2" C83600 (LG2) bar. 2" 836 is one of our common sizes and is a stocked item for us. When the production order is given to the foundry, we say that the nominal bar size is 2", so they must manufacture with the combined tolerance and machining allowance which as can be seen from the below table is between 0.03" and 0.04" on bar below 4" outside diameter. For this example, the foundry will aim to make bar which measure 2.035". Given the variations described above, we will allow bar between 2.03" and 2.04" to be put into stock. The tolerance / machining allowance chart we use is as follows:

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Busy Times at AW Fraser

July 26, 2010 Uncategorized by Matt Toohey Edit

Since I last wrote a blog, we have been experiencing the full weight of the global recovery and we are now scrambling to increase capacity while keeping costs under control and utilizing the base efficiencies we created when we were quiet last year. There are plenty of quotes floating around in world media and in our customers' own press releases about how the recession has actually been good for companies in that it allowed us all to trim waste and develop systems. Personally, I think we could all have done without it, but it is worth reporting on some of the advances we have made.

In this blog, I am focusing on our engineering expertise, particularly one of our skilled technical staff, Jody Tuckwell who is from the UK. This story is an allegory for the success of New Zealand. We are mostly an immigrant country and we are lucky that the beauty of our country, combined with a strong innovative spirit and good breweries keeps people like Jody coming here. He is an innovative engineer and has been instrumental in improving our capabilities, most recently with internal grooving on large bearings. This is keeping us competitive with low wage economies and helping us to expand the types of products we can offer our clients and also allowing us to access more clients. He is also a humorous individual and has been prompting me to write this blog! It is worth noting that the Machine Shop Technical Manager Steve Moss is an excellent UK import as well, while we have a kaleidoscope of nationals working throughout our plant, most of whom improve the national gene pool.

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AW Fraser Blog

Vertical Brass Extrusion Press Great for Hollow Brass Rod

Bronze-Web-based-ordering

Bronze Alloy Material Substituion

Bronze Tolerances and Machining Allowance

Busy Times at AW Fraser