ВДГ П690: Међународни стандардни толеранције за ливење

In the manufacturing world, precision is key, especially in casting.

Dimensional accuracy can make or break a component’s functionality, which is why tolerance standards are so important.

Међу овима, the VDG P690 standard is widely recognized for defining linear dimension tolerances in cast parts.

У овом блогу, we’ll dive into the details of VDG P690, its key aspects, how it compares to other tolerance standards, and why it is a cornerstone for quality control in casting.

1. Introduction to VDG P690

VDG P690 is a standard developed by the Association of German Foundry Experts (Verband Deutscher Giessereifachleute, VDG) that specifies linear dimensional tolerances for castings.

As casting processes can naturally lead to variations in part dimensions due to material behavior and production conditions, VDG P690 ensures that these deviations remain within acceptable limits.

This standard is used to maintain dimensional consistency, improve part reliability, and minimize potential issues during assembly.

Manufacturers across various industries rely on VDG P690 to guarantee the dimensional accuracy of cast parts, ensuring that they meet both functional and safety requirements.

Whether the application involves complex machinery, Аутомобилске компоненте, or large-scale industrial equipment, VDG P690 provides clear and detailed guidance.

2. Why Tolerances Are Important

Tolerances are critical in any manufacturing process because they define the allowable limits of deviation from the intended dimensions of a part.

In casting, where parts are often subject to shrinkage, Термално ширење, and other variables, dimensional tolerances help ensure that parts fit together correctly and perform their intended function.

Maintaining strict tolerances ensures that:

• Parts fit together correctly.
• Components function as intended.
• Quality and reliability are consistent across production batches.
• Scrap and rework are minimized, leading to cost savings.
• Customer satisfaction is maintained through reliable and high-quality products.

3. Dimensional Tolerances of VDG P690

The VDG P690 standard is structured around tolerance classes that correspond to different levels of dimensional precision.

Understanding the various aspects of this standard is crucial for both manufacturers and designers.

3.1 Линеарне толеранције

The dimensional tolerances achievable on investment castings are dependent on the following factors:

> casting material

> casting dimensions and shape

In production, the tolerance range of dispersion is affected by the varying characteristics of the materials.
For this reason, different tolerance series apply for different groups of casting materials:

• Material-group D: alloys based on iron-nickel, кобалт, and Cooper
  Accuracy grade: D1 to D3
• Material-group A: alloys based on aluminum and magnesium
  Accuracy grade: A1 to A3
• Material-group T: alloys based on titanium
  Accuracy grade: T1 to T3

Three accuracy grades are stated for each of the material groups D, А, and T.

• Accuracy grade 1 applies for all free-sized dimensions.
• Accuracy grade 2 applies for all dimensions to be toleranced.
• Accuracy grade 3 can only be met for certain dimensions and must be agreed upon with the casting manufacturer, as additional production processes and costly tooling adjustments are necessary.

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group D

	Nominal dimension домет	D1		Д2		D3
		Дкт	DCTG	Дкт	DCTG	Дкт	DCTG
	до 6	0,3	5	0,24	4	0,2	4
	преко 6 up до 10	0,36		0,28	5	0,22
	преко 10 up до 18	0,44	6	0,34		0,28
	преко 18 up до 30	0,52		0,4		0,34	5
	преко 30 up до 50	0,8	7	0,62	6	0,5
	преко 50 up до 80	0,9		0,74		0,6	6
	преко 80 up до 120	1,1		0,88		0,7
	преко 120 up до 180	1,6	8	1,3	7	1,0
	преко 180 up до 250	2,4	9	1,9	8	1,5	8
	преко 250 up до 315	2,6		2,2		1,6	7
	преко 315 up до 400	3,6	10	2,8	9
	преко 400 up до 500	4,0		3,2
	преко 500 up до 630	5,4	11	4,4	10
	преко 630 up до 800	6,2		5,0
	преко 800 up до 1000	7,2
	преко 1000 up до 1250

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group A

Nominal dimension домет	А1		А2		А3
	Дкт	DCTG	Дкт	DCTG	Дкт	DCTG
до 6	0,3	5	0,24	4	0,2	4
преко 6 up до 10	0,36		0,28	5	0,22
преко 10 up до 18	0,44	6	0,34		0,28
преко 18 up до 30	0,52		0,4		0,34	5
преко 30 up до 50	0,8	7	0,62	6	0,5
преко 50 up до 80	0,9		0,74		0,6	6
преко 80 up до 120	1,1		0,88		0,7
преко 120 up до 180	1,6	8	1,3	7	1,0
преко 180 up до 250	1,9		1,5	8	1,2	7
преко 250 up до 315	2,6	9	2,2		1,6
преко 315 up до 400	2,8		2,4	9	1,7	8
преко 400 up до 500	3,2		2,6	8	1,9
преко 500 up до 630	4,4	10	3,4	9
преко 630 up до 800	5,0		4,0
преко 800 up до 1000	5,6		4,6	10
преко 1000 up до 1250	6,6

Linear dimensional casting tolerances (DCT in mm) for dimensional casting tolerance grades (DCTG) material group T

Nominal dimension домет	Т1		T2		Т3
	Дкт	DCTG	Дкт	DCTG	Дкт	DCTG
до 6	0,5	6	0,4	6	0,4	6
преко 6 up до 10	0,6	7	0,4		0,4
преко 10 up до 18	0,7		0,5		0,44
преко 18 up до 30	0,8		0,7	7	0,52
преко 30 up до 50	1,0		0,8		0,62
преко 50 up до 80	1,5	8	1,2	8	0,9	7
преко 80 up до 120	1,7		1,4		1,1
преко 120 up до 180	2,0		1,6		1,3
преко 180 up до 250	2,4	9	1,9		1,5	8
преко 250 up до 315	3,2		2,6	9
преко 315 up до 400	3,6	10	2,8
преко 400 up до 500	4,0		3,2
преко 500 up до 630	5,4	11	4,4	10
преко 630 up до 800	6,2		5,0
преко 800 up до 1000	7,2
преко 1000 up до 1250

3.2 Angle tolerances for material groups D, А, and T

Nominal dimension домет 1)	Тачност3)
	1		2		3
	Allowed deviation од direction
	Angular минут	мм по 100 мм	Angular минут	мм по 100 мм	Angular минут	мм по 100 мм
up до 30 мм	30 2)	0,87	30 2)	0,87	20 2)	0,58
преко 30 up до 100 мм	30 2)	0,87	20 2)	0,58	15 2)	0,44
преко 100 up до 200 мм	30 2)	0,87	15 2)	0,44	10 2)	0,29
преко 200 мм	30 2)	0,58	15 2)	0,44	10 2)	0,29

Table 2: Angle tolerances

Tolerances deviating from Table 2 must be agreed on between supplier and user and entered in the drawing following DIN ISO 1101.

3.3 Radius of curvature

The tolerances stated apply to the material groups D, А, and T

Nominal dimension домет	Тачност1)
	1	2	3
	The radius of curvature [мм]
up до 5 мм	± ± 0,30	± ± 0,20	± ± 0,15
преко 5 up до 10 мм	± ± 0,45	± ± 0,35	± ± 0,25
преко 10 up до 120 мм	± ± 0,70	± ± 0,50	± ± 0,40
преко 120 мм	линеарни (cf. table 1)

Table 3: Radius of curvature for material groups D, A and T

Radii of curvature deviating from Table 3 must be agreed on with the investment casting foundry.

3.4 Surface quality

For cast surfaces, По (CLA) shall be applied following table

Површина стандарди	Материјал group Д		Материјал group А		Материјал group Т
	CLA [µinch]	Rа [μм]	CLA [µinch]	Rа [μм]	CLA [µinch]	Rа [μм]
Н 7	63	1,6
Н 8	125	3,2	125	3,2
Н 9	250	6,3	250	6,3	250	6,3

Zone N7, N8, and special surface treatment must be agreed separately and entered in the drawing following DIN ISO 1302.
Unless otherwise agreed, N9 in the shot-blasted state is the standard delivery condition.

4. Factors Affecting Dimensional Tolerances

Several factors influence the dimensional tolerances of cast parts, making it important to understand these variables when applying VDG P690 standards:

• Материјална својства: Different materials react differently during the casting process.
  На пример, aluminum and steel may experience different rates of shrinkage or warping as they cool, which can affect the final dimensions.
• Метода ливења: The choice of casting method—whether sand casting, ливење, or investment casting—can also impact the achievable tolerances.
  Ливење, на пример, generally allows for tighter tolerances than sand casting due to the more controlled nature of the process.
• Part Complexity: More intricate designs or parts with complex geometries are more prone to dimensional deviations.
  Parts with thin walls, small features, or intricate shapes may require more precise control over tolerances to ensure accuracy.

5. How VDG P690 Improves Quality Control

The VDG P690 standard plays a critical role in enhancing quality control in casting operations. Clearly defining tolerance limits.

Helps manufacturers maintain consistent product quality across batches and production runs. This leads to several key benefits:

• Смањени отпад: By ensuring that parts meet tolerance requirements, manufacturers minimize the number of rejected or scrapped parts, reducing waste and costs.
• Improved Assembly: Properly toleranced parts fit together more easily, reducing the likelihood of assembly errors and ensuring that products work as intended.
• Enhanced Customer Satisfaction: Consistency in casting dimensions leads to fewer customer complaints and warranty claims, improving overall satisfaction and building long-term trust with clients.

6. VDG P690 vs. Other Tolerance Standards

VDG P690 is one of several tolerance standards used in the casting industry. How does it compare to other standards, such as ISO 8062 or ASTM A956?

• ВДГ П690: This standard is particularly known for its detailed classification of tolerances across different part sizes and tolerance classes,
  offering more granular control over precision than some other standards.
• ИСО 8062: ИСО 8062 is a more globally recognized standard for casting tolerances and covers a broad range of materials and casting processes.
  Међутим, it is often viewed as less specific in certain cases compared to VDG P690.
• ASTM A956: Primarily used in the United States, ASTM standards provide guidelines for specific casting materials.
  ASTM A956, на пример, focuses on the hardness of cast parts rather than linear dimensional tolerances, making it complementary to standards like VDG P690.

7. Закључак

ВДГ П690 stands as a vital tool for ensuring the precision and reliability of cast components.

Its comprehensive classification of tolerance classes and flexibility in addressing different part sizes and complexities make it an indispensable standard for manufacturers.

By adhering to the VDG P690 standard, manufacturers can achieve better product performance, смањити отпад, and enhance customer satisfaction.

If you’re involved in casting or using cast parts in your products, understanding and applying VDG P690 is essential for maintaining quality and meeting the demands of modern manufacturing.

Референца садржаја：www.bdguss.de