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When designing a sheet metal part which is folded you need to understand what happens when a flat sheet of metal is fabricated or folded. To calculate the actual pattern dimensions you can use the bend allowance or bend deduction method. When the piece of sheet metal is put through the cold forming process of bending, the metal on the outside of the bend is often stretched while the inside is crushed. When this happens you can get a small extra amount of length of the part. When developing the flat pattern you need to take into account the difference in length when this is formed to get the correct dimensions on the finished component. How is Bend Allowance and Deduction Defined? By definition, the bend allowance is the arc length of the bend as measured along the neutral axis of the material you are using. By definition, the bend deduction is the difference between the bend allowance and twice the outside setback. Let us illustrate this below: The bend allowance defines the material you will need to add to the actual leg lengths of the part in order to get the flat pattern cut to a correct size. The legs of the part are the sides outside of the bend which you can see on the image below. What is the Bend Allowance Formula and how is it calculated? To calculate this bend allowance, following formula can be used: This formula takes into account the different geometries of the part you are forming and its properties. The most important aspects of this calculation are the material thickness (MT), the bend angle (B), the inside bend radius (IR) and the K- factor of the material you are bending. Note: the K-factor will typically range between 0 and .5 for most standard materials and thicknesses although some smaller and larger K-Factors are possible in certain applications. Now you've done your calculations here is our Online Shop to get you kitted out. Download our Mandrel Bend Tooling chart for precision tube bending in Aluminium, Inconel, Stainless Steel & Titanium. If you have any questions please feel free to contact one of our fabrication experts either by calling +44 (0)1844 202850 or filling out the enquiry form and we'll be in touch ASAP. #bending #bendallowance #sheetmetal #folding

At GoodFabs, we have continuously been investing in our expanding machining department. This department now consists of multiple CNC turning centres, as well as 3-axis and 5-axis CNC machines. We recently have taken delivery of a brand new 5 axis CNC machining centre from Hurco The brand new member or our machining department comes with the advanced 5-Axis Control Technology which eliminates the need to account for the machining centre’s centrelines of rotation and calculates the other locations for each of the rotary moves after the part is located to zero. This newest addition is just as our existing machinery capable of machining the most exotic materials used in exhaust systems. These materials can include Inconel, Titanium, Stainless Steel 321, etc... This enables us to create components for the urgent development exhaust systems even quicker than we already do! #CNCmachining #5axis #machining #inconel #titanium

A flow through a pipe has been discussed by many authors. A brief comparison of the different geometries regardless whether these are made out of inconel or titanium and the effects of the velocity vectors are reviewed. Flow in constant pipe When a fluid flows into a pipe, the cross sectional velocity is not uniform. The velocity vectors take a parabolic form. Where the minimum velocity is along the walls and the maximum velocity is present at the centre of the pipe flow. This profile effect is caused by the viscous wall drag created along the walls. The drag decreases with an increasing distance from the walls. Flow in a diverging pipe In the diverging pipe, the flow is not as parabolic when the cross-sectional area increases. Because the area is bigger, the velocity decreases gently in the centre and near the walls. The velocity near the viscous drag at the side is so slow that the fuel particles can accumulate with the wall Flow in a converging pipe In the converging pipe, the velocities of the flow increase as the flow enters the narrow part of the pipe. This increases the ability to transport the fuel particles. However, the fuel can accumulate against the narrowing region. Flow in a tapering pipe Tapering the pipe increases the velocity vectors. If the taper is held constant, there is no sudden narrowing region and the fuel particles are not able to accumulate with the wall. (Heisler, 1995) #inconel #Titanium #pipeflow #DidierDeLille

Inlet plenum of 4 cylinder engine Next to the design of an exhaust system and its gas dynamics, the induction system of the engine is equally as important. To ensure that the flow into the runners is following a smooth path, the upper bellmouth must be designed carefully. A bell mouth is a channel used to direct the flow at the intake of the engine, often in a straight or tapered format. In many engines where the packaging is important these could even be designed in such a way that conventional bend tooling would not allow the fabrication of these and dedictated press tooling is needed to create these. When the design is not considered a vena contracta can be formed. The vena contracta is a point in a fluid stream that passed through an orifice (or obstruction) where the diameter of the stream is smaller than the actual diameter. It decreases the actual area exposed to the flow. By removing this vena contracta the mass flow through the pipe is able to increase, aiding the volumetric efficiency of the engine. Runner without profile The straight runner without any profiles, often made out of aluminium, appears to be having problems drawing the air into the pipe; the edges prevent the runner to allow a smooth transition between the air in the environment and the pipe. This obstruction creates a significantly large vena contracta. It creates a flow obstruction in the design. This obstruction is created by a small turbulent area at the sharp edge of the runners. As the flow hits the sharp edge of the runner, the reflecting waves create a turbulent motion, obstructing the flow into the pipe at the location of the edges. This indicates that a transition between the environment and the pipe would be beneficial for the flow entering the pipe. There are different possibilities to assure that the flow from the environment has a smooth path to enter the pipe. The first possible transition would be a tangent circular edge. Runner with tangent circular profile By introducing the circular edge to the basic design, it can be seen that the vena contracta area has decreased, meaning the flow entrance would be improved. Using this circular design, the change in direction does not happen as quickly as it does without the profile and might improve the flow into the pipe. It can also be noted that the runner with the tangent circular profile is drawing air from a bigger volume than the runner without a profile. The straight runner does still show some signs of the original vena contracta, this indicates that the shape still has room for improvement. This can be done by changing the tangent circular profile to a tangent elliptical profile. Runner with elliptical profile As the presence of the vena contracta in the straight runner design indicated, the circular profile improved the flow, but still was not sufficient enough to keep the flow laminar and attached to the pipe. Therefore the circular edge design was replaced by an elliptical profile where the Semi-Major axis and the SemiMinor axis were chosen to suit the shape of the runner and assure a good transition between the environment and the pipe volume. The elliptical profiles were connected in a tangent manner so that there are no abrupt changes in the surface of the pipe. #enginepower #Inlet #BellMouth #DidierDeLille

Oxygen sensor - Lambda sensor In the automotive and motorsports industry Oxygen sensors (also known as O2 sensors) are often used to monitor the air-fuel ratio in the cylinders and to control the emissions, or increase the performance of the engine. We briefly explain the why, how and what on these sensors? Exhaust emission control The oxygen sensors or Lambda sensors are used to make the modern electronic fuel injection and emission control in many internal combustion engines possible. The sensors are generally located in the exhaust pipe. These oxygen sensors provide real time information to the engine control unit about the air-fuel ratio of the last combustion in the cylinder. By providing the information to this unit, the injection of fuel can be changed to increase the efficiency of the engine and reduce the emissions of hydrocarbons, carbon monoxide and NOx gases (nitrogen oxides) by trying to achieve a stoichiometric air-fuel ratio. In general there are 2 commonly used oxygen sensors. In the production automotive industry a so called ‘narrowband’ lambda sensor is generally used while in many forms of motorsports a more expensive ‘wideband’ lambda sensor is used. Narrowband Lambda sensor The narrowband lambda sensor (or O2 sensor) can only determine three types of mixtures in the exhaust gases. Is the mixture either Rich, Stoichiometric or Lean. It cannot provide information on how rich or how lean the exhaust gas mixture is to the engine control unit (ECU). When this sensor is used, the ECU reads the signal and decides to either increase or decrease the amount of fuel injected in the cylinder by a set value and do this over and over again to reach the stoichiometric readings. Since this sensor only provides a limited amount of information, this sensor is not suited to be used in the development of exhaust systems and a wideband O2 sensor could provide a solution. Wideband Lambda sensor The wideband oxygen sensor can provide a lot more information about the mixture and can do this in real time. Opposite to the behaviour of the narrowband lambda sensor, where only rich, stoichiometric or lean signals can be read this sensor is able to provide the exact air-fuel ratio the engine (or cylinder) is currently running at. Because of the real time information, this sensor is ideal to evaluate development exhaust systems and engine control settings. How does it work The narrowband oxygen sensor is generally based on a solid-state electrochemical fuel cell. It consists of two electrodes which provide a certain output voltage depending on the amount of of oxygen in the exhaust system relative to that in the atmosphere. The sensor creates a DC output voltage between 0.2V and 0.8V where the lower value represents a lean mixture and the higher value represents a rich mixture. When a voltage of approximately 0.45V is generated the mixture is seen as optimal for emisions which is ~0.5% lean of the stoichiometric ratio of the air-fuel mixture. At this point, the exhaust gases contain a minimal amount of carbon monoxide. The voltage produced by the sensor is nonlinear with respect to oxygen concentration. The sensor is most sensitive near the stoichiometric point (where λ = 1) and less sensitive when either very lean or very rich. The wideband oxygen sensor (often known as UEGO sensors) however is also based on a planar zirconia element, but has an incorporated electrochemical gas pump. This pump is controlled with a closed loop feedback which keeps the output of the electrochemical cell at a constant ratio. Because of this feedback loop, the sensor provides a very accurate real time signal of the air-fuel mixture in the exhaust system. This sensor operates on a voltage between 0.5V and 4.5V and has a wider signal band where a lower voltage represents a leaner air-fuel ratio and a higher voltage represents a richer air-fuel ratio. Increasing engine power by changing air-fuel mixture To increase the engine power it is often said that optimising the air-fuel mixture is one of the key aspects. A properly tuned engine with a calibrated air-fuel ratio is indeed critical for optimal performance and durability of the engine. The theoretical a stoichiometric air-fuel ratio is the perfect ratio of fuel and air which in a gasoline engine is 14.7:1. This means that 14.7 units of air are needed to perfectly combust 1 part of gasoline fuel. This value is different for every other type of fuel. When a leaner mixture is used, there is more air than needed present in the combustion chamber which can result in a higher combustion temperature. The opposite happens when there is more fuel than needed in the combustion chamber. It is known that normally aspirated spark ignition engines produce the most power when the air fuel mixture is just slightly rich of the stoichiometric value of 14.7:1. Generally this value is kept between 13:1 and 12:1 to keep the exhaust gas temperatures as low as possible without losing power. When using a turbocharged engine, as Formula 1 currently does, an even richer air-fuel ratio could be needed to reduce the knocking effect in the engine. Because the turbocharged air entering in the cylinder has an increased density and a denser mixture, the cylinder peak pressure and temperature could be significantly higher than it would be in the normally aspirated spark ignition engine meaning there could be an increased danger of knocking if this is not cooled down by running a richer mixture. #lambdasensor #enginepower #DidierDeLille #oxygensensor

GoodFabs is launching GFMoto, our new motorcycle exhaust brand, at The London Motorcycle Show at Excel, which starts on Friday 17th February and ends on Sunday 19th February. Come and see us on Stand R111 and watch the video to see what we will have on show. #BMWS1000RR #Alloys #AfricaTwin #Titanium #Inconel #GoodFabs

GoodFabs designed V8 Formula 1 exhaust The design of an exhaust system is usually a trade off between engine performance, packaging, materials available and the fabrication techniques used. Every type of exhaust has its own challenges. In most of the formula racing series such as Formula 1 the packaging area around the engine is very tight where specialist tooling is needed to create the sometimes-complex transition shapes. On motorcycles one would think that the packaging space is unlimited and there are no packaging constraints, however one could not be more wrong! Trying to follow the contours of the bike as much as possible for packaging and esthetic reasons and still maintaining the best flowing systems to increase the engine performance can be quite a task for the best designers. On top of these challenges, the exhaust designer needs to take into account what materials and its fabrication and forming techniques can be used in the application. In exhausts there are only a limited amount of regularly used materials, which are: Steel, Stainless Steel, Nickel alloys and Titanium. Stainless Steel The most common used materials in the automotive industry outside of motorsports are steel and stainless steels. Since these are the cheaper option and they are more readily available these are more suited for a production environment. On top of this, these materials are easy to work with and require close to no special processes for cold forming, fabrication or welding. Tig welding an exhaust part at GoodFabs As every material has its limitations, so do steel and stainless steel. These materials sometimes lack strength and corrosion resistance at higher temperatures. Because of this a thicker wall would need to be used to ensure the strength in the exhaust system is sufficient, which would cause the exhaust system to be a heavy part of the engine assembly. A perfect material to tackle this weight problem would be Titanium with its very lightweight properties. Titanium Titanium as an alloy for exhaust applications is a relatively strong and very light material, but at higher temperatures it can oxidize when the oxygen diffuses into the surface. This is why the welding process of these Titanium alloys needs to happen in an inert atmosphere. Nickel Alloys The last group, and most expensive, of exhaust system materials are the nickel alloys. These materials are specifically created for the use in high temperature applications with an increased corrosion resistance and strength! Because of these superior properties to steel, stainless steel and Titanium, nickel alloys such as Inconel are perfect for higher demanding exhaust applications such as those in a motorsport as Formula-1, Le Mans series, Touring cars, Moto GP, etc.. Because of the strength in these nickel alloys it is found that a lighter but stronger exhaust system could be created using these rather than titanium which is well know for its low weight. In recent applications GoodFabs has used wall thicknesses of less than 0.35mm in racing applications without failures! Because of the highter melding points of nickel alloys, the strength and stiffness involved due to the work hardening properties, the cold forming, welding and fabrication process can be more expensive and labour intensive than any of the other materials. Inconel cold formed pressed transitions at GoodFabs #Titanium #stainlesssteel #DidierDeLille #Alloys

Delta Motorsport have developed the MiTRE electric car range extender to ease 'range anxiety' for existing electric car owners. GoodFabs assembled the first prototype of this highly efficient turbine unit, which is designed to generate additional battery power on the move. At the beginning of 2016 GoodFabs were consulted on the feasability of fabricating an inconel prototype by Simon Dowson, Managing Director of DeltaMotorsport, who had worked with GoodFabs in 1990s while at Reynard. Phil Levett agreed to help with the ground breaking project which had secured funding from Innovate UK, the UK Government's innovation agency. AN INCONEL MASTERCLASS Based on their experience advising marine, defence and motorsport companies on a range of engineering projects Delta specified inconel for the prototype in order to avoid any issues that might arise from excessive heat. GoodFabs used a range of fabrication and machining techniques including pressings, machining and TIG welding, to create the prototype, which enclosed a sophisticated 3D printed heat exchanger. Multiple fabrication techniques were used to create customised inconel parts The final 17kw prototype assembled by GoodFabs helped prove the concept, which is now being developed in a 35kw format with a view to a commercial roll out with automotive customers in Europe. GoodFabs and DeltaMotorsport have both won recent awards as part of the Silverstone cluster of companies, based in Buckinghamshire and Northamptonshire, that serve Formula 1 and other top motorsport engine builders and teams located in the UK's Motorsport Valley. Machining, pressing and DMLS techniques were used to create a fully TIG welded inconel part #welding #Inconel #MiTRE #DeltaMotorsport #GoodFabs

WHAT IS SHOT PEENING? Shot peening is a separate cold working process designed to increase the exhaust life cycle by producing a compressive residual stress layer on the outer surface, which modifies the mechanical properties of the metals. WHY ARE STRESSES PUT IN THE MATERIAL? The residual tensile stress from welding metals such as inconel, stainless steel and aluminium is created because the weld consumable is often applied in a liquid state. The welding process heats the metal and the weld is applied in its hottest, most expanded state. When the much cooler consumable material is bonded to the base material, the weld tends to cool rapidly and will attempt to shrink from the ‘drop in’ temperature. Because the base material is usually much stronger and not in a molten state, this cannot shrink, leaving the material remaining in a highly stressed “tensioned” state. This zone is usually just next to the weld joint, which explains why a crack may appear close to the weld. HOW DOES SHOT PEENING WORK? The shot peening process impacts the metal surface with small pellets (round metallic, glass or ceramic particles) with a high enough force to deform the surface plastically. A compressive layer is generated when the impact of all the particle shots produce small indentations in the top surface layer. The layer beneath the top surface is then compressed, generating a compressively stressed layer underneath the shot peened area. This layer helps to prevent the stressed area from cracking as a crack cannot propagate in a compressive environment. The shot peening process has been proven to be very beneficial in many components operating in a highly-stressed environment such as motor racing. TYPICAL SHOT PEEN BEHAVIOUR The graph below [D1] shows a typical situation of a welded metal component before and after shot peening. As can be seen from the graph, the residual stresses in the welded metal are positive, which puts the surface layer in a tensional state. When shot peened the material is compressed and the residual stresses are negative, putting the material in the compression state where the cracks cannot propagate. This graph illustrates how the residual stresses after shot peening are the most negative in the layer underneath the shot peened top layer and gently increase as we go deeper in the material. This graph does not refer to any specific material and is purely for illustration purposes.[G2] SHOT PEENING QUALITY STANDARDS All shot peening processes are rigidly quality controlled and regulated by a series of SAE standards that control the process, media used, etc.. Shot Peening Media SAE-AMS-2431. Automatic processing SAE-AMS-2430 Computer controlled processing SAE-AMS-2432 Almen Strips & Gauges SAE-J442 Almen Strip usage SAE-J443 GoodFabs manages both the shot peening and heat treatment processes as part of an exhaust programme for a race team or engine builder. Inspection is normally required both before and after heat treatment and shot peening, so GoodFabs coordinates both procedures prior to final delivery of the finished and inspected part to the customer. #stainl #inconel #shotpeening #stress #welding #DidierDeLille

GoodFabs has helped the GB Skeleton team with their world beating sled ever since they were approached by McLaren Applied Technologies back in 2010. Great Britain is the most successful nation without its own practice track in the sport of Skeleton. Since the discipline was introduced into the Winter Olympics in 2002 the women’s team have won medals in every Winter Olympics. Amy Williams won gold in the Vancouver games in 2010 and Lizzy Yarnold repeated the feat in Sochi in 2014. After winning bronze in 2002 and silver in 2006, the University of Southampton was approached by the English Institute of Sport (EIS) to create a competitive skeleton capable of being used by both male and female athletes. The two young naval architects who took on the task - and succeeded in delivering a sled that helped win the first gold medal four years later - were transferred in 2010 to Formula 1’s McLaren Applied Technologies unit. At McLaren they were asked to refine and develop their winning sled using techniques and technology developed in F1. Issued with materials from Skeleton’s official federation, the IBSF, they were introduced to a series of F1 suppliers who would be able to bend, machine and weld the steel runners used as part of the skeleton to create the most efficient sliding mechanism possible. GoodFabs was the fabrication company that McLaren recommend to carry out the welding work. Six years later GoodFabs is still working with the British Bobsleigh and Skeleton Association (BBSA) to try and complete a hat-trick of gold medals at the 2018 Winter Olympics in Pyeongchang, South Korea. As usual there is plenty of secrecy involved as other teams try and replicate the technology to give their own athletes an added edge. Unfortunately, we cannot reveal details of our work on the skeleton, although it continues to challenge us and requires all the techniques and experience that one would expect when working with a team striving for more gold. Go GB! In 2019 a further development of the runners was undertaken where we were able to fabricate these runners to the highest precision again. After thorough testing the runners made it to the World Championship. When we received the below message, we were all proud of what was achieved and are happy to be part of this success! "Just wanted to let you know that the following athletes are using the runners we have made in the last few months and all are working well. Better speeds and closer to the more experienced group of athletes out here at the World champs" GB Gold Medallist Lizzy Yarnold prepares for a slide Donna Creighton of the 2017 GB Women’s Skeleton squad #GBSkeleton #BBSA #LizzyYarnold #SteelRunners

Developing an inconel exhaust system for a special Subaru GoodFabs worked with Roger Clark Motorsports' Gobstopper Time Attack cars and developed a custom-made and heat-shielded twin scroll inconel manifold finished with white ceramic coating to suit a very tight engine bay. The name Roger Clark is well known by many motorsport fans and has its roots in the racing and development of rally cars from the 1960s to the present day. Founded by the late Roger Clark himself, the company is now run by sons Matt and Olly and is based in Leicestershire in the United Kingdom. Their latest Time Attack development is Gobstopper II, their 780bhp Subaru Impreza STI that won the Goodwood Festival of Speed Hill Climb this year. At GoodFabs, we were privileged to help make this car what it is today. Gobstopper I Back in 2010, Roger Clark Motorsports (RCM) approached GoodFabs to help develop an exhaust system to suit their Gobstopper I Time Attack car. After some discussions with Phil Levett and Geoff Rayner at GoodFabs to work out the objectives of this development, the 1999 Impreza STI was brought to our workshop in Long Crendon, near Oxford for a couple of weeks. When the car was finished, RCM tested the new exhaust and clocked a staggering 780bhp on the engine. The Gobstopper I car was too much for the competition and quickly became one of the most popular racing Subarus. Gobstopper II In 2014, the development of the new Gobstopper II began and once the development of the chassis was finished, it was time to create a new exhaust system to suit the new 2008 Subaru Impreza STI based Time Attack car, using the same base engine as the Gobstopper I. Since the development of the exhaust system for the original Gobstopper was a success, RCM quickly knocked on the door of GoodFabs again. Sadly, this was one of our busiest times of the year with Formula 1 and we unfortunately had to decline the project. As no time could be wasted, RCM had to turn to another race exhaust supplier, who developed a small and tight exhaust system to suit available space to fit the Garett hybrid 4094 twin scroll turbo. When the system was finished and tested, various runs on the dyno proved that the car had lost about 70bhp. In March 2015, RCM contacted GoodFabs to ask if we could develop a system which delivers the full 780bhp again. At this time we were able to take on this challenge. When the car was brought to the workshop, it quickly became clear that this would not be easy. The new Time Attack car still had the EJ20 - Closed Deck, 2000cc boxer engine, but also had a very close underfloor with very tight constraints. Since the exhaust system also needed to be heat shielded, the constraint package became even tighter. When we had an initial look at the system developed by the other company, some fundamental problems were discovered. The diameters of the exhaust system were too large which reduced the exhaust gas velocity and had a negative effect on the turbo. A second apparent problem was the centrelines used on this system; they appeared to be very tight, which is very detrimental to exhaust gas flow. Since GoodFabs owns a massive range of bend tooling, we were able to use the largest possible centrelines to keep the flow inside the system optimal. Also, the experience we already had with Gobstopper I and the entire Prodrive Subaru Rally programme quickly enabled us to create a system with the correct diameters and an optimised flow geometry. Heat shielding Gobstopper II When the system was fully finished within the constraints, GoodFabs' in-house heat shielding department tailored an inconel 625 custom-made heat shield in order to retain all the exhaust energy inside the system so it could be fully utilised in the turbo. When the full exhaust was finished, this was again tested on the engine dyno to prove out the system and remap the engine. The results showed that the lost 70bhp had been completely restored and RCM could live up to its stated aim of "Always Pushing, Always improving, Making the Best Better, the Fastest Faster, the Impossible Possible, Perfecting the Perfect". This was impressively demonstrated at Goodwood in front of an international audience made up of motorsport's elite. #Subaru #Exhaustdesign #DidierDeLille #Timeattack #Inconel625

Titanium Grade 1 is also known as commercially pure titanium and is one of the softest titanium grades with high formability and excellent weldability. Because it is lightweight, with good corrosion resistance, this material is often used in exhausts on motorbikes and other applications where bends and shapes are required. Physical Properties/ Mechanical Properties Titanium cannot be hardened by heat treatment. However through hot forming, the springback will reduce and the overall ductility of the material will increase. It is possible to cold work titanium - its behavior is similar to that of austenitic stainless steels. Composition Titanium comes in different categories: commercially pure titanium which is unalloyed alloyed titanium Each has their strengths and weaknesses. The table below only shows values for the commercially pure titanium where grade 1 is the softest titanium with the highest ductility but the lowest strength through to grade 5 which offers the highest strength but only has a moderate formability. Machining and Welding Titanium is not a nightmare to machine, as some might say. Many machinists compare the behavior of this material to stainless steel 316 where a high coolant flow is needed together with a slow speed and high feed rate. Titanium has good weldability properties because of its nature as a single-phase material. Consequently, the mechanical properties of the weld are equal to or even better than the parent material and no post-welding heat treatments are needed. Titanium is known to turn blue when this is heated. This is because it is a reactive metal where it reacts to heat by creating an oxide layer of a blue color. #Titanium #Materialproperties #DidierDeLille #Specialistmaterials