More information.

Stepan V. Lunin.

2007.

Figure 1. Spiral bevel ZAKgears that can be produced without use of high cost gear manufacturing machines.

India, China, Russia, Vietnam, South America and other countries have been showing strong economical development. The demand for new manufacturing machines and new manufacturing processes is high. However, the availability of investment capital is limited.

ZAKGEAR has developed a production process for power transmission gears at significantly reduced capital investment. The basic elements of the ZAKGEAR production method was born during the romantic time of the Cold War between the United States of America (USA) and the Union of Soviet Socialist Republics (USSR). During that old time the USA export control did not allow selling Gleason spiral bevel technology to the USSR. The federal authorities believed that the subject technology would benefit Soviets in manufacturing more cost-effective geared transmissions for land and air combat vehicles. Ironically, US embargo worked out not exactly the way it was intended. It catalyzed development of a better technology in Russia. Russkies learned on other people's mistakes and started to build their own spiral bevel gear machines in Saratov. Gleason spiral bevel software was not available in the USSR even for its six-digit price tag. Russian engineers would have to figure out calculation of machine summary by themselves. Software package named VOLGA has been developed. It was reported to be more accurate spiral bevel summary calculation tool compare to other software. It has to be noted that at that time Gleason calculated summary would not provide the final summary at the first cut. Russian professor Segal was one of the major spiral bevel theoreticians in Russia. When retired, he moved to Germany and was employed by Klingelnberg until he died. Before moving to Germany Professor Segal proposed an idea of a CNC gear cutting machine. The underlying idea of the Segal's concept was to control the motion of the gear cutting tool not by a complex gear transmission but by linear and rotary actuators that would follow to the commands from a computer program. Segal's CNC gear machine concept was too advanced for that time. Later Klingelnber, Oerlikon, Gleason, MG Minigears, and other companies reduced Segal's idea to practice. Other talented scientists have made significant contribution to the CNC gear cutting idea. Dr. Herman Stadtfeld has done tremendous work in publishing about advantages of the CNC gear-cutting concept while employed by Klingelnberg, Oerlikon, and Gleason. Klingelnberd, Oerlikon and Gleason have build new machines. However, the increase of the cost for the CNCgear cutting machine did not pay back by increasing of productivity and quality. MG Minigears have proved that retrofitting of the existing machines can be up to 3 times more cost effective compare to purchasing of new CNC controled gear cutting machines. In 1999 MG Minigears have started spiral bevel production in Vitginia Beach, VA using its own CNC controlled machines. While developing their own spiral bevel gear theory Russian engineers have noticed root disadvantages of the Gleason face milling method, such as non conjugated nature of the tooth generating process. The new process was proposed, which allowed manufacturing spiral bevel gears on Gleason like machines, but with simplified geometry, which does not require over complicated calculation of the machine summary. Over 50,000.00 tanks deployed in Eastern Europe by Soviet is an example of the effectiveness of the alternative technology. For comparison, US TACOM was able to finance production of some 5,000.00 similar ABRAMS tanks. The new process of making spiral bevel gears allows reduction on the capital investment when starting of new spiral bevel gear business. The term LEAN did not exist during the Soviet time but working smart instead of working hard (California relaxing working stile was common in the USSR) and reduction of intellectual waist (focusing on achieving the result instead of wasting effort on documenting the process) was the bottom line of the Soviet industry during the time of limited financial resources. The alternative spiral bevel technology was one of the good examples of applying LEAN for R&D and product development. Using of spiral bevel and hypoid ZAKgear technology allows to produce higher quality product by "not working hard, but working smart". ZAKGEAR offers a smarter way of making gear. It is a better way to do gear business when the initial financial resources are limited and when the maximization of the profit margin is required when reduction of time on the investment return is critical.

Figure 2. Budgetary estimate of the capital investment for starting a new business in production of spiral bevel and hypoid gears.

Why does one have to pay $2,000,000.00 US for a machine to cut a traditional spiral bevel gear if one can cut a spiral bevel ZAKgear on a $200,000.00 CNC machine?

Why does one have to pay $1,000,000.00 for a "state of the art" gear cutter sharpening machine for the traditional spiral bevel gear if spiral bevel ZAKgear can be cut by a $10.00 standard mill cutter?

Why does one have to pay big money for old technology if better technology is available for less money?

Figure 3. Advantage of low capital investment in spiral bevel ZAKgear versus high capital investment in the traditional spiral bevel gear business.

Because the traditional spiral bevel gear business has been around for a long time it is difficult for new gear businesses to compete with existing and well-established companies. Starting a business in the field of production of traditional spiral bevel gears requires an over sized initial investment.

Figure 4. Thanks to lower capital investment spiral bevel ZAKgear business pays back sooner and return on the investment is higher.

Because the competition in the traditional gear production is very high, the return on the investment will be low. Spiral bevel ZAKgears does not require high capital investment. Because spiral bevel ZAKgears cost less compare to the traditional spiral bevel gears the return for the investment is higher.

Figure 5. Comparison of the traditional gear against spiral bevel ZAKgear.

Spiral bevel ZAKgears are quieter and stronger in comparison to the traditional spiral bevel gears. The performance advantage of spiral bevel ZAKgears makes ZAKgear suitable for high performance applications such as helicopter or motor sport transmissions like FORMULA ONE or NASCAR. While ZAKGEAR technology provides numerous advantages the simplest way to explain advantage of spiral bevel ZAKgear is to refer to the research results published by NASA gear research center in Cleveland, OH, in 2001. The results of the extended test have been published in Report NASA/TM-2001-21-940, "Experimental Comparison of Face-Milled and Face-Hobbed Spiral Bevel Gears" by Robert F. Handschuh and others. NASA tests demonstrate noise reduction and load capacity increase on face-hobbed (Oerlekon like) gears compare to the traditionally used in the aerospace (Gleason like) face-milled spiral bevel gears. Face-milled spiral bevel gears are traditionally used on high performance application thanks to the possibility to grind such of gears after case hardening process. Face-hobbed gears can not be finished by grinding and it makes it impossible to produce a high accuracy face-hobbed gear for high speed dynamic application. Spiral bevel ZAKgear tooth form is not identical but it is very close to the face-hobbed tooth form. However the little difference in the tooth geometry allows using the traditional spiral bevel tooth grinding process for finishing of spiral bevel ZAKgears. One can think about a spiral bevel ZAKgear like one would think about a Klingelnberg or an Oerlikon gear that can be finished by common gear grinding process. Frankly, spiral bevel ZAKgear is a grindable face-hobbed (Oerlikon like) gear. Spiral bevel ZAKgear has all the advantages of the face hobbed gear. It offers reduced sensitivity to misalignment, reduced noise, and increased load capacity. But in addition to that a spiral bevel ZAKgear can be finished by grinding with simple ZAKGEAR machine summary using the existing spiral bevel grinding machines. ZAKGEAR provides free online calculator to calculate of machine summary for grinding spiral bevel ZAKgear on Gleason, Oerlikon or on other existing spiral bevel grinding machines.

Figure 6. Improved 3-dimensional CAD model of spiral bevel ZAKgear tooth surface that can be used for manufacturing on a common ($200,000.00 US) 4-axis CNC milling machine up to AGMA quality class 10. After CNC machining the gear can be finished by grinding on a common spiral bevel grinding machine. The summary for grinding machine can be calculated for free on ZAKGEAR online calculator web site.

Spiral bevel ZAKgear is stronger, quieter and less sensitive to manufacturing errors compare to the traditionally manufactured spiral bevel gears. It is well-known that the geometry of the traditional gear is limited by the capabilities of the traditional gear cutting machine. The limitations of the tooth geometry result in limitations of the gear performance. ZAKgears do not have limitations in tooth geometry of the gears produced on Gleason or on Oerlikon machines. For example, ZAKgear tooth lead and/or tooth profile can be optimized for highest performance of the gear.

Figure 7. 3-dimensional CAD model of spiral bevel ZAKgear tooth surface, which has modified tooth profile and topological lead correction for increased load capacity, increased driving efficiency, and for noise reduction.

Gleason or Oerlikon machines do not restraine geometry of spiral bevel ZAKgear because ZAKgear do not require to be produced on such of machines. The mathematical modeling of the gear cutting and Tooth Contact Analyses (TCA) are also more advanced on ZAKgears compare to the traditional TCA because ZAKgear technology is based on Direct Digital Simulation (DDS). DDS method is used for mathematical modeling of the tooth geometry and for simulation of the tooth contact.

Figure 8. Spiral bevel ZAKgear 3-dimensional CAD model of an immediate tooth contact at different load conditions.

Developing of the tooth contact is an expensive stage of manufacturing of the traditional spiral bevel gear because the traditional TCA software is not capable to reverse engineer the machine summary in order to produce the required tooth contact. The traditional TCA software can only simulate what the tooth contact will look like for the given machine summary. ZAKgear technology allows reverse engineering of the manufacturing setting based on the desired tooth contact and the transmission error. Perfectly ovaloid tooth contact is possible on spiral bevel ZAKgears with little or no extra TCA development cost.

ZAKgear spiral bevel technology is less expencive compare to the existing spiral bevel technology. The current advance in CNC machining offers significant cost reduction in design and manufacturing of spiral bevel gears and other ZAKgears. While the modern spiral bevel gear and hypoid generating machines (like machines from Gleason or from Oerlikon) are, frankly, over priced modifications of the gear machines that were produced 50 years ago, the modern CNC 4-5-axis milling machines have gone a long way in improvement, cost reduction and productivity. If to look back on the development history of spiral bevel and hypoid gear machines one would wonder why the prices went up for 10 times, but productivity and the accuracy has only got a marginal improvement. It would not be mistake to predict that the prices for spiral bevel gear cutting equipment will continue to grow in double digit rate without offering tangible value added. On the other hand, CNC milling machines have got significant improvement in productivity and, more importantly, they have dropped significantly in cost. Most likely CNC machines will continue its drastic improvement in productivity and the price will continue to reduce.

Figure 9. ZAKGEAR provides a 3-dimensional model of the gear so the root stress can be calculated on standard FEA software.

Figure 10. Bending strength on spiral bevel ZAKgear can be increase for 50% by adding flange on the Heel and modified root on the Toe.

Figure 11. ZAKGEAR manufacturing method allows novel design solutions. It would be impossible to manufacture the ring gear with the shaft on Gleason or Oerlikon machines because of the interference between the shaft and the cutter.

What would be a better investment strategy if one wants to invest in spiral bevel business? Should one continue investing into technology that is continuously increasing its cost without offering tangible value. Or, would it be a better investment in progressively improving technology, which demonstrates proven record of the significant reduction of its cost and offering innovative technological solutions for making new products? I have answered this question for myself by investing my own time into writing this article about an affordable ZAKGEAR method of making spiral bevel gears. ZAKGEAR method is out there and ready to serve your business while offering opportunities that the traditional methods can not provide.

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