Subsurface-Damage-(SSD)PPT课件
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Subsurface Damage (SSD) 次表面损伤
-
1
SSD
• Managing SSD during the shaping process and removing SSD during the polishing process is essential in the production of laser quality optics.
• We know that grinding is nothing more than the controlled fracturing of glass, and we know this fracturing can lead to SSD. We know that this SSD can often be hidden under a redeposition layer which requires chemical etching to see. Since we seldom have the opportunity to acid etch all our parts, in process, we have to be conscious of what is happening during our grinding process. What we’ve done at VLOC is a series of experiments to understand our process and maintain our process parameters.
• 玻璃铣磨是在物料上盘后，硬的研磨剂在被加工玻璃表面进行旋转研 磨运动的过程。 碎裂会导致材料的去除和SSD产生。表面机械损伤是 由研磨过程中产生的表面微裂组成。这些表面缺陷微观定义为划痕与 点子，它们常常因为含水层的折射率匹配而被隐藏，只有在通过化学 蚀刻后才能被发现。
-
5
Understanding Grinding
• 表面损伤是指在易碎光学材料近表面上的一些残余碎裂和 变形的材料。残余碎裂和变形的损伤层通常在砂轮切削、 铣磨和研磨操作时产生，这些操作过程典型使用在光学元 件的初始加工和成型中。-3SSD Shaping
• SSD切削 • Due to their high removal rates, lapping and grinding are used universally
-
7
Understanding Grinding
• Next we had to understand how much material to remove in grinding. We did this by acid etching parts after certain stock removals and by measuring surface roughness both before and after the acid etch. We learned that different diamond wheels and machines in the shaping area played a huge role in how much material had to be removed in grinding. We determined that by removing 0.13mm – 0.20mm per side, we will have removed all the SSD from the previous operation.
• 在切削加工时控制SSD及在抛光加工时去除SSD在光学激光 产品生产中是很必要的。
• We will discuss what SSD is and how to control it, monitor it and hopefully minimize it.
• 我们将讨论什么是SSD以及如何控制，监控和如何将损伤 减至最小。
-
2
SSD
• Subsurface damage refers to the residual fractured and deformed material in the near surface region of brittle optical materials. This layer of deformed and fractured material is generally the result of abrasive cutting, grinding and lapping operations that are typically used during the initial figuring and shaping of the optical component.
• 在课程中我们学习了在铣磨中使用到研磨液和一些惯例做法。当研磨 液中的砂砾磨成小颗粒时，磨削速率将变慢，操作员会加入新的研磨 液来提高磨削速率。这样能使新的研磨液均匀中散布一些大的新的颗 粒，而不是均匀的磨钝的颗粒。这样在抛光前，肉眼是不能看到玻璃 水化层深划痕。
• 首先我们研究粗砂，采用9µm 研磨粉加工零件。这个粗砂有9, 9T and 9B。未处理过的9， pH ≈9.5，9T加入悬浮液、pH ≈4.5，9B的研磨液的 pH ≈8.5。因为9T的PH值低 ，所以它能快速的切削。但是对于铣磨工 具来说这样还是腐蚀性太大了，这样会导致产品表面锈斑。这种锈蚀 很难去除的。这就是为什么我们最后会选择9B作为研磨剂。
• First we studied the grit. We finish our parts with 9µm Microgrit. This grit comes in 9, 9T and 9B. The un-treated 9 has a pH ≈9.5, the 9T has a suspension agent and a pH ≈4.5, and the 9B has a suspension agent and a pH ≈8.5. Because of the 9T’s low pH, it has quicker stock removal BUT it also is more corrosive to the cast iron grinding tools so it leaves rust stains on the glass parts. This rust is very difficult to remove. This is why we chose the 9B to be our final grinding grit.
• 我们知道铣磨只不过是一种受控的玻璃碎裂过程，我们知道这些碎裂 会导致SSD的产生。当SSD隐藏在沉积层下，只有通过化学反应才能被 发现。我们极少机会把所有的零件都用酸刻蚀，但是，我们意识到在 铣磨过程中发生了什么事情。VLOC的做法是在连续的试验中了解操作 过程和过程参数。
-
6
Understanding Grinding
• We also use slurry in grinding and learned a hard lesson about a common practice. As the slurry grit broke down in particle size, the removal rate would get slower, so our operators would ‘spike’ their grit with fresh grit to improve the removal rate. This lead to the ‘load’ being distributed over a few large, fresh particles, rather than evenly over all the particles. This caused deep scratches that weren’t visible due to redistribution of glass (hydrated layer) until polishing.
for shaping optical components. Because fracturing is the dominant mechanism for material removal during grinding and lapping operations, subsurface damage is inevitably introduced during the shaping process. During shaping, SSD is minimized by the use of a series of grinding steps where successively smaller abrasives are used to remove the subsurface damage introduced during the previous operation. The final vestiges of SSD, from grinding and lapping, can be removed by polishing, provided that sufficient material can be removed without introducing additional SSD during the polishing operation. • 得益于研磨和铣磨的高速切削，他们被普遍应用于光学元件的成型。 在铣磨和研磨过程中碎裂是材料去除的主要机理，因此成型过程中表 面损伤是避免不了的。在成型过程中，通过一系列的研磨步骤能将 SSD降至最低，不断减小研磨粒度来去除上道加工留下的表面损伤。 假如抛光过程磨削足够的材料并且没有引入额外的SSD的话，在研磨 产生的SSD的残余能通过抛光来消除。
• 接下来我们要了解在铣磨过程中有多少材料被去除。磨削后的零件使 用酸蚀刻前后，分别测量表面粗糙度。在下料区里，不同的金刚石砂 轮和机器能使材料在研磨中起到了很大的作用。每一面去除0.13mm – 0.20mm ，我们能去除先前操作所带来的所有SSD。
-
8
Understanding Grinding
-
4
Understanding Grinding
铣磨
• Grinding of glass can be described by brittle fractures caused by an ensemble of normally loaded, hard indentors (abrasive) rolling across the surface of the glass work piece. The brittle fracture will lead to both material removal and development of SSD. Subsurface mechanical damage consists of surface micro-cracks that occur during the grinding process. These surface cracks, typically identified microscopically as scratches and digs, are often hidden below an index matched hydrated layer or have closed so they are not detectable until exposed by chemical etching.
-
1
SSD
• Managing SSD during the shaping process and removing SSD during the polishing process is essential in the production of laser quality optics.
• We know that grinding is nothing more than the controlled fracturing of glass, and we know this fracturing can lead to SSD. We know that this SSD can often be hidden under a redeposition layer which requires chemical etching to see. Since we seldom have the opportunity to acid etch all our parts, in process, we have to be conscious of what is happening during our grinding process. What we’ve done at VLOC is a series of experiments to understand our process and maintain our process parameters.
• 玻璃铣磨是在物料上盘后，硬的研磨剂在被加工玻璃表面进行旋转研 磨运动的过程。 碎裂会导致材料的去除和SSD产生。表面机械损伤是 由研磨过程中产生的表面微裂组成。这些表面缺陷微观定义为划痕与 点子，它们常常因为含水层的折射率匹配而被隐藏，只有在通过化学 蚀刻后才能被发现。
-
5
Understanding Grinding
• 表面损伤是指在易碎光学材料近表面上的一些残余碎裂和 变形的材料。残余碎裂和变形的损伤层通常在砂轮切削、 铣磨和研磨操作时产生，这些操作过程典型使用在光学元 件的初始加工和成型中。-3SSD Shaping
• SSD切削 • Due to their high removal rates, lapping and grinding are used universally
-
7
Understanding Grinding
• Next we had to understand how much material to remove in grinding. We did this by acid etching parts after certain stock removals and by measuring surface roughness both before and after the acid etch. We learned that different diamond wheels and machines in the shaping area played a huge role in how much material had to be removed in grinding. We determined that by removing 0.13mm – 0.20mm per side, we will have removed all the SSD from the previous operation.
• 在切削加工时控制SSD及在抛光加工时去除SSD在光学激光 产品生产中是很必要的。
• We will discuss what SSD is and how to control it, monitor it and hopefully minimize it.
• 我们将讨论什么是SSD以及如何控制，监控和如何将损伤 减至最小。
-
2
SSD
• Subsurface damage refers to the residual fractured and deformed material in the near surface region of brittle optical materials. This layer of deformed and fractured material is generally the result of abrasive cutting, grinding and lapping operations that are typically used during the initial figuring and shaping of the optical component.
• 在课程中我们学习了在铣磨中使用到研磨液和一些惯例做法。当研磨 液中的砂砾磨成小颗粒时，磨削速率将变慢，操作员会加入新的研磨 液来提高磨削速率。这样能使新的研磨液均匀中散布一些大的新的颗 粒，而不是均匀的磨钝的颗粒。这样在抛光前，肉眼是不能看到玻璃 水化层深划痕。
• 首先我们研究粗砂，采用9µm 研磨粉加工零件。这个粗砂有9, 9T and 9B。未处理过的9， pH ≈9.5，9T加入悬浮液、pH ≈4.5，9B的研磨液的 pH ≈8.5。因为9T的PH值低 ，所以它能快速的切削。但是对于铣磨工 具来说这样还是腐蚀性太大了，这样会导致产品表面锈斑。这种锈蚀 很难去除的。这就是为什么我们最后会选择9B作为研磨剂。
• First we studied the grit. We finish our parts with 9µm Microgrit. This grit comes in 9, 9T and 9B. The un-treated 9 has a pH ≈9.5, the 9T has a suspension agent and a pH ≈4.5, and the 9B has a suspension agent and a pH ≈8.5. Because of the 9T’s low pH, it has quicker stock removal BUT it also is more corrosive to the cast iron grinding tools so it leaves rust stains on the glass parts. This rust is very difficult to remove. This is why we chose the 9B to be our final grinding grit.
• 我们知道铣磨只不过是一种受控的玻璃碎裂过程，我们知道这些碎裂 会导致SSD的产生。当SSD隐藏在沉积层下，只有通过化学反应才能被 发现。我们极少机会把所有的零件都用酸刻蚀，但是，我们意识到在 铣磨过程中发生了什么事情。VLOC的做法是在连续的试验中了解操作 过程和过程参数。
-
6
Understanding Grinding
• We also use slurry in grinding and learned a hard lesson about a common practice. As the slurry grit broke down in particle size, the removal rate would get slower, so our operators would ‘spike’ their grit with fresh grit to improve the removal rate. This lead to the ‘load’ being distributed over a few large, fresh particles, rather than evenly over all the particles. This caused deep scratches that weren’t visible due to redistribution of glass (hydrated layer) until polishing.
for shaping optical components. Because fracturing is the dominant mechanism for material removal during grinding and lapping operations, subsurface damage is inevitably introduced during the shaping process. During shaping, SSD is minimized by the use of a series of grinding steps where successively smaller abrasives are used to remove the subsurface damage introduced during the previous operation. The final vestiges of SSD, from grinding and lapping, can be removed by polishing, provided that sufficient material can be removed without introducing additional SSD during the polishing operation. • 得益于研磨和铣磨的高速切削，他们被普遍应用于光学元件的成型。 在铣磨和研磨过程中碎裂是材料去除的主要机理，因此成型过程中表 面损伤是避免不了的。在成型过程中，通过一系列的研磨步骤能将 SSD降至最低，不断减小研磨粒度来去除上道加工留下的表面损伤。 假如抛光过程磨削足够的材料并且没有引入额外的SSD的话，在研磨 产生的SSD的残余能通过抛光来消除。
• 接下来我们要了解在铣磨过程中有多少材料被去除。磨削后的零件使 用酸蚀刻前后，分别测量表面粗糙度。在下料区里，不同的金刚石砂 轮和机器能使材料在研磨中起到了很大的作用。每一面去除0.13mm – 0.20mm ，我们能去除先前操作所带来的所有SSD。
-
8
Understanding Grinding
-
4
Understanding Grinding
铣磨
• Grinding of glass can be described by brittle fractures caused by an ensemble of normally loaded, hard indentors (abrasive) rolling across the surface of the glass work piece. The brittle fracture will lead to both material removal and development of SSD. Subsurface mechanical damage consists of surface micro-cracks that occur during the grinding process. These surface cracks, typically identified microscopically as scratches and digs, are often hidden below an index matched hydrated layer or have closed so they are not detectable until exposed by chemical etching.