校准和产品准确性认证

在精密测量仪器和计量中,对于用户来说精度和可靠性是很重要的两个方面。在仪器读数不准确后作出的决定将会导致意外后果。 Digi-Pas®精密数字水平仪和倾角仪采用公司专有的先进校准和制造工艺,针对大范围工作温度下的非线性进行校准。为了提高透明度,确保公正性和能力,Digi-Pas®产品的精确性能已经经过众多世界领先认证机构的外部验证,这些认证机构采纳运用了可追溯至NIST,JIS,UKAS和DIN标准的超高精度的纳米技术车床和角度干涉仪。

Digi-Pas®产品标准性评估的校准证书来自独立认可的第三方和世界领先的国际计量实验室(CIPM MRA)。 Digi-Pas®产品的精度性能按规格进行测试,并由美国,日本,英国,德国和中国合格评定国家认可委员会的认可校准和测试实验室定期反复验证,可在国际实验室认可合作组织(ILAC)下,追溯至NIST,JIS,UKAS, DIN和中国CNAS。美国实验室认证协会(A2LA),保证了在全世界范围内的接受度合格评定。

我们工厂的生产设备和角度测试仪器会定期得到我们研究实验室精密角度测量设备的校准,然后在美国,日本,德国,英国和中国合格评定国家认可委员会接受进行外部第三方独立认证的横向再次认证(见下面的校准证书样本)与DATA)。每批生产测试数据(包括校准文件)均按照ISO9001程序进行维护,并由相关方和当局根据要求提供。只有那些高精度型号都需带有硬拷贝的工厂QA校准证书和数据。

如果客户希望购买某个产品,并附带硬拷贝的第三方校准证书以及任何产品型号的DATA,请联系我们的销售支持团队以获取报价。一些精密型号可用于Amazon.com USA的第三方校准证书和DATA。

以下校准证书样本为用户提供了在您所在地区附近选择合格的第三方校准服务提供商的选项。这些服务提供商拥有专业的精密角度测试设备和专业知识,能够符合ISO / IEC 17025:2005标准,以测试我们产品的独特功能,特别是(i)2轴同时角度测量,(ii)及其广泛的测量范围,(iii)超高的精度。 Digi-Pas®仪器的质量体系确保生产的产品符合规格。通过填写“联系我们”表格,可以索取最新工厂的校准证书和/或外部校准证书。

Three-Point Contact Base of Digi-Pas® 2-axis Precision Inclinometer


  1. Limitations of conventional rectangular contact base levelling instrument

    The contact base surface finish quality of a typical conventional leveling instrument or inclinometer is one of the critical determinants of accuracy performance and common rectangular-shape flat surface often suffer from geometrical deviation resulting from:

    • Waviness and unevenness
    • Irregularities due to distorted or worn surface
    • Dust and dirt trapped or surface roughness

    Figure 1 illustrates three typical poor surface finishes of conventional rectangular surface four-point contact base. The unstable surface-to-surface contact causes 'rocking' which results in measurement inaccuracy derived from inconsistent readings. A common practice to improve the outcome under such constraint is by taking more samples to obtain an averaged reading. However, this time-consuming and repetitive activity often promotes boredom that succumb engineers to resort for compromising works, especially when the instrument is located at some distance.

    Figure 1 Poor surface finishes of typical levelling instrument contact base and implications
    Figure 1: Poor surface finishes of typical levelling instrument contact base and implications

    Although high quality surface requires both flatness and smoothness, it is difficult and expensive to control in machining of metal alloy surface particularly when involving relatively large area. Increasing the flatness and smoothness of a few microns would usually increase exponentially on its manufacturing costs. This often results in a trade-off between the manufacturing costs of the instrument and thus compromises its accuracy performance.

    In addition, the rectangular contact base surface of a conventional leveling instrument is also susceptible to target measuring surface unevenness, which is another factor affecting levelling and measurement accuracy. Figure 2 illustrates issues associated when a rectangular contact base of a traditional single-axis spirit level is placed on a typical machined surface having low frequency, long wavelength flatness variation. It is clearly shown that full and stable surface-to-surface contact could not be achieved between the instrument base and the measuring surface. The contact may cause rocking that results in measurement errors, hence affects the accuracy and reliability of the leveling outcome. E.g. a 3µm of surface unevenness along the length of a typical 20µm/m resolution spirit machinist level of 130mm would result in 0.001° error

    Figure 2: Conventional single-axis contact base on a two-dimensional uneven plane
    Figure 2: Conventional single-axis contact base on a two-dimensional uneven plane
  2. Digi-Pas® concave contact base versus 'perfectly flat' contact base structures

    Often, dents are easily generated on smooth metal base area of an instrument resulting from rough handling. A protruding dent formed at any location near the middle of a 'perfectly flat' metal base simply causes rocking which results in measurement error or inaccuracy. To minimize these errors, Digi-Pas® instrument metal surface base has been deliberately designed and machined to form a concave 4-points contact base specifically target to prevent rocking caused by small protruding dents or foreign particles formed at the center of device’s base. Figure 3 illustrates the inferiority of a 'perfectly flat' base of conventional instruments against the improved design of Digi-Pas® concaved 4-point base when small dents/particles exist at the center of device’s base. It is obvious that small dents or particles exist near the middle of the base shall not affect stability of Digi-Pas® instrument as it is supported by both ends having precisely machined stable contacts to the targeted measurement surface.

  3. Figure 3. Side view of perfectly flat contact base versus Digi-Pas® concave 4-point base
    Figure 3. Side view of perfectly flat contact base versus Digi-Pas® concave 4-point base

    On the other hand, dents formed at the both ends of the instrument may not necessarily cause significant rocking. When dents happen at these both ends, an offset value/reading caused by these dents can be easily removed using Digi-Pas® calibration or Absolute Level feature (see “Accuracy Performance”). In contrast, a protruding dent formed at the middle of the device’s base destabilizes the device with severe rocking during measurement which cannot be resolved by using calibration or Absolute Level feature. This phenomenon does not only affect the instrument's initial offset value, it also affects the repeatability of measurement reading.

    Thus, the contact surface approaching the base center of instrument is deliberately being designed with a concave profile to minimize the above issue, providing improved stability of measurement readings as well as enhances accuracy of the instrument.

  4. Pioneering the application of 3-point contact base in 2-axis precision levelling instrument

    In view of the constraints inherent in conventional contact base measuring instrument described in the foregoing, Digi-Pas® pioneered and patented the utility of 3-point contact base for its 2-axis precision angular and surface flatness measurement instruments. The triangular shape of 3-point contact base seeks to address the shortcomings associated with conventional rectangular contact base.

    Figure 4: Stable 3-point-to-surface contact between Digi-Pas® inclinometer and flat surface object
    Figure 4: Stable 3-point-to-surface contact between Digi-Pas® inclinometer and flat surface object
    Figure 5: Stable 3-point-to-surface contact between inclinometer and uneven surface
    Figure 5: Stable 3-point-to-surface contact between inclinometer and uneven surface

    When a 3-point contact base leveling instrument is placed on either flat or uneven surface object (e.g. typically machined metal surface) as shown in figure 4 and 5 respectively, the three-point frame serves as a triangle-plane platform for supporting the weight and maintaining the stability of the instrument. It provides maximum stability and strength against downward forces and horizontal forces as well as movements about horizontal axes. With the sturdy three-point stand, a most stable 3-point-to-surface contact can be established without rocking and thus achieving consistent leveling readings of the two-dimensional measuring surface. Any angular deviations on the surface area is detected by Digi-Pas® 2-axis inclinometer as sensitive contact points touch on a particular section of uneven surface area.


  5. Advantages of Digi-Pas® 3-point contact base levelling instrument

    In 2009, Digi-Pas® pioneered and patented the utility of 3-points contact base to its world-first 2-axis precision digital level series that effectively prevent any surface dimensional deviation caused by unevenness of its own instrument’s metal surface contact base. Figure 5 illustrates the 3-point contact base screws made of harden steel and titanium materials that offers great stability and prevent it from ‘rocking’ when placed on either flat or uneven smooth surface for 2D levelling and planar angular measurement.

    Figure 6: Digi-Pas<sup>®</sup> patented 2-Axis Precision inclinometer utilizing 3-Point Contact Base
    Figure 6: Digi-Pas® patented 2-Axis Precision inclinometer utilizing 3-Point Contact Base

    Maintaining the 3-points contact is easy, speedy and cost effective simply by replacing the harden/titanium screws whenever they wear off, saving significant amount of time and cost as compared to maintain the instrument’s contact base surface finish through standard machining. Device accuracy performance can also be re-calibrated by performing User Self-Calibration or “Absolute Level” setting at ease. Please refer to user manual for detail instructions.

    For using Digi-Pas® 2-axis inclinometer to level an object having a very rough top surface, the 3-point harden/titanium screws can be temporarily removed and use the flat base surface to naturally average the rough surface. Absolute Level Setting is required to be performed immediately after changing the base to ensure the instrument maintains its reference accuracy. However, in high precision leveling, angular measurement and surface profiling tasks usually involve high quality flatness and smooth surfaces such as granite and metal alloy machined surfaces. Hence, 3-point contact base is still a better choice.

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