POWERTRAIN FOR LARGE MINING EQUIPMENT – 5-AXIS

Author: Felix    Position: Project Manager

This project is the latest developed powertrain for the American company SIGMA. SIGMA’s electric motor assembly is applicable in multiple fields. This is a powertrain designed for large mining sites,

Regarding project：

with a metal casing specifically for CAT 777 and CAT 797 applications. It is equipped with a 5MKW and 5-speed gearbox and is mainly used for large-scale transportation equipment in mining sites.

Project introduction:

The parts has two sets in total. The material of the main body, nameplate and bottom cover is pure 6061-T6. The central-axis is made of SAE1070 spring steel.The dimensions of the main body are 693.6*687.5*600mm. The single product weighs around 141.8kg. The size of the bottom cover is 865.0*862.2*197.0mm. and the product weighs around 64.5KG，the internal cover size is 610.0*610.0*91.0mm, weighing 23.8Kg. Altogether the whole product weighs around 250KG. As the inside of the main body is all cut out by CNC machining, the weight of the material to be ordered is much more than the weight of product, so one piece requires us to order 840KG of material.

Incoming material inspection:

The whole project took around 20 days. Due to the heavy material, in order to ensure the project could be completed according to the plan, each step needs care and attention. Firstly, the material is 6061-T6.In addition to the material certificate provided by the suppliers, we also need to do a toughness test for the incoming material. As the material size is too large, each side of material has to undergo a toughness test at 10 points to ensure the material has been hardened.(incoming material toughness inspection)

3-axis CNC roughing:

The raw material of the main body weighs around 840KG. Due to the weight, 5-axis equipment cannot be used here as there is a need of second processing to meet up the standards of drawing sheet. Firstly, carried out the 3-axis roughing and left 1mm on one side of the part. Due to the large amount sof cutting, the crystal structure inside the part may change. Thus, the part must undergo stress treatment, which will effectively reduce the risk of cracking. (Whole machine assembly)

5-axis CNC precise processing:

The parts after roughing weighs around 150KG and thus a slow rotating speed must be maintained during 5-axis intermodal processing to ensure accuracy and normal processing.( 5-axis CNC precise processing)

Parts cleaning and polishing

Firstly, after the processing with 5-axis equipment is done, the parts will be polished and cleaned. The polishing is 2-step. Firstly, we will polish the corners to ensure a smooth transition at the corners of the product. （First polishing).

There will be dust on the part surface after the first polishing, so we still need to clean the part. During the cleaning, we need to use the, finer sandpaper to polish the surface of the parts, and the surface quality of the cleaned and polished parts is more glossy. (Cleaning parts)

Second polishing：

Finished product display：

Inspection

After polishing and cleaning, the parts will undergo inspection. The nameplate, shaft, and middle cover will undergo 3D inspection, while the main body and bottom cover, two large parts, will undergo inspection by scanning.

Before inspection, the parts need to be cleaned and labeled with light spots. The distance between the light spot markings should be spaced according to the size of the parts, with a distance of 10-15mm.(Main body scanning detection)

Scanning of the bottom cover:

The details, like tooth shape and depth will be checked to ensure that all tooth shapes meet the design standards.

(Checking all tooth shapes with a stop and go gauge)

For the tooth depth, we customized all the required screws, and conducted inspection on all the tooth shapes.(tooth shape depth inspection)

Main scanning computer screen：

Bottom cover scanning computer screen：

The tolerance of the scanning equipment is within 0.02mm, while for critical dimensions we use tools such as plug gauges and calipers for verification. If special positions cannot be verified, specialized tools need to be customized for verification.

Main scanning report：

Bottom cover scanning report：

After our report was approved by the customers, we selected an appropriate packaging method according to the size of the parts. As the parts are heavy, to avoid any accidents during the transportation, we have chosen to package individual products separately, using a 10T thick foam to wrap the product inside. The wooden box is made of thick boards with added metal corners to reduce transportation risks and ensure the integrity of the parts.

Packing details“”

Left rear 45 degree angle of parts after painting：

Left front of parts after painting：

Parts Exhibition：

Grefee owns over 200 sets of equipemt from different brands, including Fanuc, Makino, Mikron Charville, Kwanyu, LGMAZAK, etc including 16 high-precision 5-axis machines. The maximum size that can be machined is 3500mm * 1800mm * 1200mm, (5-axis workshop)

5-axis machining of parts：

3D inspection of parts：