production notes

Arrow Precision manufacture components of exceptional quality in an industry known for its exacting standards. Our components will out-last and out-perform the competition, offering the customer excellent value for money. Arrow Precision design strength in and pay attention to detail, the only way to get a lightweight, robust rod and real quality.

material specification
We manufacture from the highest quality steel, specified and purchased by us, from mills in the UK. Vacuum de-gassed nickel chrome alloy steel (Double-air-re-melt) has a very low sulphur content, .025%, which means fewer inclusions and faults. When forged, imperfections are reduced to an absolute minimum, ensuring excellent consistency in the six standard forgings reaching our machine shop. We refer to this steel as EN24. EN24 (817M40 British Standard) as used by Arrow Precision for most rods, is comparable to 4340 AISI/SAE, which is available as both air melt and vacuum remelted steel, checks should be made when comparing manufacturers just what type of 4340 is being used. 4340 is higher in hardenability than any other standard AISI grade. Other names for 4340 include Werkstoff 1.6565 and Kurzname 40 CrNiMo 6. Other steels used include 300M which is a silicon modified steel with slightly higher carbon and molybdenum contents, plus some vanadium. This is a vacuum remelted steel with deep hardenability along with ductility and toughness. It has no comparable steel names.

manufacturing process
Before the machining process can begin a detailed drawing of the connecting rod is sent out for your approval. A tensile and reciprocating load analysis will have been carried out and the design produced with the help of our unique CAD programmes. Drawing details include material spec, bushing requirements, special machining needs and of course dimensions and fastener types. Once you have ensured the spec meets with your requirements, your order will be scheduled in our machine shop and a firm delivery given and achieved. Our engineer will then write the machine plan including the selection of raw materials. From as few as one to hundreds of quality rods can be produced using flexible manufacturing lines and unique processes.

During production all facets of the forgings are machined to ensure symmetry and balance, and to remove any potential flaws. Having been split, the big end is then torqued up using slave bolts. We work closely with our fastener suppliers, to ensure the correct bolt is selected for each application, and point out the importance of attaining correct stretch in each fastener (Please see our hints and tips booklet).

We have enhanced surface hardening considerably by introducing a new peening process. All peening is now fully automatic and exposes the rod to an exact level of steel shot peening in a controlled and uniform manner. This allows 100% consistency to be achieved right across the surface of the rod, removing stress raisers and reducing further the chance of stress fractures forming. By carrying out tests we have determined the saturation point on a graph allowing us to achieve optimum hardness and consistency across many hundreds of components.
After the peening process the slave bolts are removed and the correct bolts torqued up in their place. The rods are finish ground and balanced end to end, to within a gram.

inspection
On each operation a recorded sample inspection is carried out. Our magnaflux crack detection unit tests all our rods in our specially constructed dark room and prior to dispatch a full sample inspection and 100% visual is undertaken. The adherence to ISO 9001:2000 enables us to monitor all materials and processes from beginning to end, helping us to guarantee an excellent product.

identification
Finally and uniquely, every rod produced is laser etched with the company logo, but more importantly, a date of manufacture, a part designation and a set number. Many manufacturers mark their products with a stamp, not only can this be hard to read but it can also harm the integrity of the item. Just another reason to buy from Arrow Precision.