CATEGORIES
Contact Us

Qingdao Shengmei Machinery Co.,Ltd

Address: No.6 Wangjialou Industrial Area, Huangdao District, Qingdao City, China

Contact: Sandry Pang

TEL: +86-532-85131608

Moblie: +86-18660248878

Fax: +86-532-86158266

Email: shengmei@shengmeicast.com

Home > Exhibition > Content

China vacuum process casting machines

Qingdao Shengmei Machinery Co.,Ltd | Updated: Sep 19, 2017
Source:

Product Application:

Vacuum mold casting, also known in manufacturing industry as the V process, employs a sand mold that contains no moisture or binders. The internal cavity of the mold holds the shape of the casting due to forces exerted by the pressure of a vacuum. Vacuum molding is a casting process that was developed in Japan around 1970.

Vacuum molding[edit]

A schematic of vacuum molding:

Vacuum molding (V-process) is a variation of the sand casting process for most ferrous and non-ferrous metals,[6] in which unbonded sand is held in the flask with a vacuum. The pattern is specially vented so that a vacuum can be pulled through it. A heat-softened thin sheet (0.003 to 0.008 in (0.076 to 0.203 mm)) of plastic film is draped over the pattern and a vacuum is drawn (200 to 400 mmHg (27 to 53 kPa)). A special vacuum forming flask is placed over the plastic pattern and is filled with a free-flowing sand. The sand is vibrated to compact the sand and a sprue and pouring cup are formed in the cope. Another sheet of plastic is placed over the top of the sand in the flask and a vacuum is drawn through the special flask; this hardens and strengthens the unbonded sand. The vacuum is then released on the pattern and the cope is removed. The drag is made in the same way (without the sprue and pouring cup). Any cores are set in place and the mold is closed. The molten metal is poured while the cope and drag are still under a vacuum, because the plastic vaporizes but the vacuum keeps the shape of the sand while the metal solidifies. When the metal has solidified, the vacuum is turned off and the sand runs out freely, releasing the casting.[7][8]

The V-process is known for not requiring a draft because the plastic film has a certain degree of lubricity and it expands slightly when the vacuum is drawn in the flask. The process has high dimensional accuracy, with a tolerance of ±0.010 in for the first inch and ±0.002 in/in thereafter. Cross-sections as small as 0.090 in (2.3 mm) are possible. The surface finish is very good, usually between 150 and 125 rms. Other advantages include no moisture related defects, no cost for binders, excellent sand permeability, and no toxic fumes from burning the binders. Finally, the pattern does not wear out because the sand does not touch it. The main disadvantage is that the process is slower than traditional sand casting so it is only suitable for low to medium production volumes; approximately 10 to 15,000 pieces a year. However, this makes it perfect for prototype work, because the pattern can be easily modified as it is made from plastic.[7][8][9]

Main Features:

1. V-process is known for not requiring a draft because the plastic film has a certain degree of lubricity and it expand slightly when the vacuum is drawn in the flask. 
2. The process has high dimensional accuracy.
3.no moisture related defects, no cost for binders, excellent sand permeability, and no toxic fumes from burning the binders
4.the pattern does not wear out because the sand does not touch it.
5.Take good use of sand, the material recovery rate is 95%.

Feedback
Qingdao Shengmei Machinery Co.,Ltd

If you have any enquiry about quotation or cooperation, please feel free to email us at shengmei@shengmeicast.com or use the following enquiry form. Our sales representative will contact you within 24 hours. Thank you for your interest in our products.

Copyright © Qingdao Shengmei Machinery Co.,Ltd All Rights Reserved.