The lowest is “commercial,” which is followed by “aircraft quality.” ARP uses only the top two grades , which cost twice as much, but provide the foundation for defect-free fasteners. Series NBF and NBL track rollers are designed with heavy outer ring cross section for track roller applications. They offer a corrosion resistant alternative to conventional yoke type cam followers. RBC stud type cam followers have a new Hexlube® feature and come equipped with a grease fitting installed in the flanged end of the stud. Thread milling requires less machine horsepower, so is better suited to smaller machines than tapping large threads. The usual motivation for indexable tooling is cost–you can replace an insert rather than the entire tool. However, as is the case with most indexable tooling types, the geometry and therefore the performance of equivalent solid carbide tooling is superior.
This article provided a review of thread rolling including the machines used, production rates, materials, pitch diameters, and machine speed and feed rates. Learn more about threads and threading from the Machinery’s Handbook, 30th Edition, which is published and available from Industrial Press on Amazon. Screw threads may be formed by rolling either by using some type of thread-rolling machine or by equipping an automatic screw machine or turret lathe with a suitable threading roll. The thread-rolling process is applied where bolts, screws, studs, threaded rods, etc., are required in large quantities. Screw threads that are within the range of the rolling process may be produced more rapidly by this method than in any other way. Because of the cold-working action of the dies, the rolled thread is 10 to 20 percent stronger than a cut or ground thread, and the increase may be much higher for fatigue resistance. Other advantages of the rolling process are that no stock is wasted in forming the thread, and the surface of a rolled thread is harder than that of a cut thread, thus increasing wear resistance. However, when parts are produced in larger quantities, single point threading’s versatility is less beneficial.
As the company strives to continuously update its manufacturing operations, Superior has installed modern CNC machining equipment. To assure improved quality and increased productivity, Superior relies on its in-house CAD/CAM computer and LAN to reduce lead times and improve quality. Using this technologically advanced equipment, Superior performs more manufacturing “Miracles” than ever before. Superior focuses on the machining and thread-rolling on nonstandard parts, especially high heat-treated machined parts. This process requires close attention to details, flawless manufacturing planning and flight-safety parts approvals. Superior, manufacturing is a rigidly controlled process converting raw materials into high-quality finished products. Superior purchases raw materials or uses customer-supplied stock. Manufacturing output includes bolts, pins, clevis parts, special actuator screw and nut assemblies, and special high-strength parts fabricated from various new alloys. These machines, the largest of those used by the company today, have enough power to cold form or hot roll some of the toughest exotic materials at heat ranges exceeding 50 Rockwell.
Threaded fasteners either have a tapered shank or a non-tapered shank. Fasteners with tapered shanks are designed to either be driven into a substrate directly or into a pilot hole in a substrate. Mating threads are formed in the substrate as these fasteners are driven in. Fasteners with a non-tapered shank are generally designed to mate with a nut or to be driven into a tapped hole. to 6 in (6.35 to 152.40 mm) or longer, with the coarse threads of a wood-screw or sheet-metal-screw threadform . This distinction is consistent with ASME B18.2.1 and some dictionary definitions for screw and bolt. Visitors were able to see the results of extensive plant expenditures over the last two years including investments in new production machining equipment, inspection equipment, process flow improvements and employee work areas. This year marked a major expansion, with the opening of National Machinery China, in Suzhou. This wholly-owned facility serves as customer support in service and parts for China, along with the production of the newly introduced LeanFX and PumaFX FORMAX machine models. Our growth continued and not just with the new products we developed but with the purchase of E.J.
Pontiac’s Engineering learned early on that cutting-edge camshaft design could put its production V-8s on the forefront of the performance market. It spent a great deal of time developing and testing various valve timing combinations to determine exactly what its engines performed best with. Generally speaking, larger engines can tolerate more duration without negatively impacting low speed performance. The amount of camshaft duration a combination performs best with must match the size and intended operating range of the application. Other factors such as the position of the Intake Centerline and Lobe Separation Angle can be used to slightly improve idle quality or low speed street manners, or broaden the entire power band. During development the block’s lifter bores were designed to deliver an adequate volume of pressurized oil for proper hydraulic lifter operation.
As the material will be plastically deformed by pressure, it should have a minimum elongation factor of 5% to 7%. Cast Iron, pure bronze, hard brass alloys and other hardened materials that have less than 5% elongation are too brittle to be thread rolled. It can process triangular thread, ladder pattern, straight line, net pattern, twill and so on. Many times, parts are received for service in bulk packaging, but when they are returned with shiny precision threads, they are individually packaged with protectors to prevent damage during shipment. On one recent day, a clerk was packing up a single blue container that was lined with padded foam. Left-handed screw, multiple thread screw, worm, knurl, serration, pipe-thread, burnishing, etc. General screw, left-handed screw, multiple thread screw, worm, knurl, serration, pipe-thread and burnishing can be manufactured. Incorporates hydraulic operation and can be applied to through and infeed rolling up to 32mm diameter components.
Since there are so many solid-lifter options, I suggest contacting the manufacturer to determine whether those you are considering are self-regulating and include high-pressure bearing oiling. Expect to spend $500 or more on a quality set of solid-roller lifters, and I am comfortable recommending any of those above. A few companies producing solidroller lifters for the Pontiac V-8 have found a solution that greatly improves reliability. Comp Cams, Crane Cams, and Crower Cams each offer Pontiac-specific lifters that direct a constant supply of pressurized oil to the roller wheel and axle assembly to positively lubricate the needle bearings. The lubrication cools and cushions bearings, significantly lengthening service life. Isky also produces solid-roller Pontiac V-8 lifters, and one is available with a low-friction roller that’s free of needle bearings to maximize strength in the most severe applications. The valley pan is an integral part of a Pontiac’s PCV system and oil vapors are continually passing through it. It’s not uncommon to find heavy sludge deposits caked inside an original.
When passing the roll over the work, there is a tendency to raise the cross-slide. Where the part to be threaded is tapered, the roll can best be presented to the work by holding it in a cross-slide roll-holder. Relation that the thread rolling operation bears to the other operations. In a thread-rolling machine, thread is formed in one passage of the work, which is inserted at one end of the dies, either by hand or automatically, and then rolls between the die faces until it is ejected at the opposite end. Some form of mechanism ensures starting the blank at the right time and square with the dies. This machine can also be used in the in-feed process with parallel die axes, the length of the profile to be rolled depends of the width of the rolling dies, there is no axial movement of the workpiece. This ensures optimum capacity and use in making threads and axially parallel profiles in the through-feed process. However, short cylindrical parts can also be rolled in the through-feed process. For this special through-feed process automatic feed of the work is necessary.
Camshaft duration can be measured at most any point of lifter rise and fall. “Advertised” duration is typically the amount of crankshaft rotation recorded between .006 inch of lobe rise and .006 inch of lobe fall. Advertised duration can have different meaning for different manufacturers, however. Aftermarket manufacturers began providing duration specifications at .050- inch lobe lift so consumers could compare various cams and predict the performance effects. That particular value was selected because it’s a reference point that easily measured and it’s about the point that significant airflow begins. A camshaft opens and closes the valves at specific points during crankshaft rotation. Those values, along with a few others makeup the “timing” or “events” of a particular cam.
The quick lobe action of a solid-roller camshaft and the valvespring pressure required to control it are very hard on the roller wheel and its bearings. Comp Cams and Crower each offer solid-roller lifters for the Pontiac V-8 that includes a jet of oil that positively lubricates the bearing area. These two contain similar .050-inch duration and valve lift specifications, but the roller lobe reaches peak valve lift much quicker and maintains it longer than the high-performance flat-tappet . Hydraulic roller cams are very popular in modern performance builds. They increase performance while providing a quiet valvetrain that requires little maintenance. A cam and lifter set like this from Comp Cams costs several hundred dollars, but you get what you pay for. Comp’s hydraulic roller lifers are among the best available today. Roller lifters use a larger roller wheel to reduce the sliding friction associated with a flat-tappet cam.
A large internal grease cavity assures maintenance-free service. Needle Roller Cam Followers have a heavy outer ring cross section and a full complement of needle rollers. They offer high dynamic and static load carrying capability, and anti-friction performance, in a compact design. They are used as track rollers, cam followers, and in a wide range of linear motion systems. Our rules for selecting a thread mill require no more than 70% of hole diameter for threadmill diameter. So we want a threadmill that is no more than 0.350″ in diameter. I like Lakeshore Carbide’s tooling , so I will go choose a threadmill from his online catalog. A Spiral Flute Thread Mill can cut faster than Single Profile Thread Mills because more than one thread can be cut by the multiple rows of teeth. The same Spiral Flute Thread Mill can cut lefthand or righthand threads and it can vary the diameter of the threads, but they are limited to a single thread pitch governed by the spacing of their teeth. Lost a piece or need a smooth surface component for working with soft or delicate material?
The amount of time an intake or exhaust valve is off its seat is referred to as “duration” and it’s expressed in degrees of crankshaft rotation. Since the crankshaft must rotate twice to complete a single four-stroke cycle, the timing set gears are appropriately sized so that the camshaft operates at half the speed of the crankshaft. As the camshaft rotates, the oil trapped beneath the plunger is pressurized and bleeds outward as the plunger further reacts against valvespring pressure. This bleeding is referred to as “leakage,” and the rate at which a lifter leaks is controlled by using various degrees of lifter-body-toplunger clearance during manufacturing. Pontiac literature generally lists only the advertised duration for its camshafts. Measuring duration at .050-inch lobe lift simplifies camshaft comparisons and gives a more accurate indication of the effects a particular camshaft has on total engine operation. The lifter fixture with dial indicator from Comp Cams is part of the camshaft degree kit I routinely use.